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Novel Carbocyclic Ring Closure of Hex-5-enopyranosides.

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Keywords: glycosylations . N M R spectroscopy * oligosaccharides . solid-phase synthesis . synthetic methods
I
95
~
2)
1001
C'3 x i 3
5 1 50 49 48 47 4 6 4 5 4 4 4 3 42 41 4 0 3 9 38 37
/I
-
-6
Figure 2. I h g n o s t i c region of the 'H-'.'C
H M Q C N M R spectrum o f 3
Thc spectra show that HR-MAS can bc used for monitoring
the solid-phase synthesis of oligosaccharidcs in a very sensitive
fashion. Parenthctically, the measurements tend to confirm our
earlier claim that solid-support coupling rcactions -using properly protected 1,2-anhydro sugars (at least in this series)- are
highly stereoselective. even morc so than the solution-based
couplings." 'I The original claim was based on thc finding that
no a-linkcd products could be found upon cleavage from the
polymer and subsequent purification. Of course, arguments of
this sort arc subject to uncertainties as to whethcr other stereoisomers might have been inadvertently overlooked during the
removal and purification sequcnce. The argument becomes
more persuasive as one cxamines thc "crude reaction mixture"
bound to the solid phasc. While the data we obtaincd cannot
exclude adventitious overlapping of signals from small amounts
of isomcric %-products, it certainly indicates a high degree of
control of each coupling event conducted on the solid phase.
We attribute this exccllent B-stereoselectivity in this and related
solid-state experiments19, l o ] to the relative diminution of cffective solvation upon complexation of thc oxirane by the zinc
chloridc promoter. Solvation forces can lend the anomeric
oxiranyl donor oxonium-like qualities. A donor spccies, which
is far advanced in the direction of a free oxonium ion, is likely
to be responsible for the formation of small but significant
amounts of a-glycosides from the solution-based a-epoxide
donor.
In summary, the development of novel methodologies for thc
assembly of oligosaccharides on the solid support will undoubtedly benefit from this disccrning "on-resin" analytical method.
Chemists will be able to determine whether coupling has occurred and quickly estimate the specificity of the coupling step.
Complete assignments can be madc aftcr the product is cleaved
from the solid support and deprotected.
E,qwitnenfal Section
All specti-a were obtained on a Bruker DKX500 spectrometer. operating a t
500.13 M H r ( ' H ) and 125.76 MHz ("C). equipped with a 4 m m Bruker CCA
HR-MAS probc. Trisaccharide 3 (20 mg at 0.54 nimo1g-l loading, 10.8 pmol) was
loaded into a ceramic rotor. suspended in 30 p L CDCI,, and spun at the magic angle
at 3.5 K H r ' H N M R spectra were obtained with a Carr-Purcell~Meihoom-(iill
pulse sequence [13]. 128 transients (1.64 s acquisition time. 0.5 s relaxation delay)
were accumulated. The 13C['H: spectrum was obtained in 2 h 10 i n i n
(3000 transients. 0 6 s acquisition time. 2 s relaxation delay). The phase-sensitive
(TPPI) ' H - "C H M Q C spectrum was obtained i n 2 h (16 scans per 256 increments.
0.17 s acquisition time, 1.3 s relaxation delay) with a BIRD sequence to minimi7e
resin sigiials "41. Total time for ' H , "C. and H M Q C N M R experiments was 4 h
15 inin.
Received. July 3, 1996
Revised vcrsion' October 7. 1996 [Z9291 IE]
German version: A n p i i ' . C k m . 1997. I O Y , 507 510
A. Giannic. Afigeii. U i e i i 7 1994. 106. 188: Aii,cyir. Ciiriii. / f i r Ed. h g l . 1994.
33. 178: C.-T. Yuen. Bezouska. J. O'Brien. M Stoll. R. Lcmoine. A. Lubineau.
M. Kiso. A. Hasegawa. N.J. Bockovich. K . C. Nicolaou, T Feizi, .I Biol
Chcv??.1994, 269, 1595; A. Vxki, P m . Nritl. A r i d Sri USA 1994. 91, 7390.
M 1. Phillips. t. Nudelrnan. E C. A. Gaeta. M. Perm. A. K. Singhal, S
Hakamori. J. C. Paulson, S<I(WP1990. 250. 1130. L.M Stoolman. Ceii 1989,
56, 907; L A Lasky, ihiri 1992. 258. 964
K. 0 . Lloyd, Ani .I Chi Prithoi. 1987. 87, 129, C. A. Ryan. P i o r ' iV(/r/. Amid
Sci. USA 1994, Y l , I ; M. Meldal. S. Mouritsen. K Bock i n C(/i-h(~/i~,r/i.~iti,
Antigms (Eds: P J. Garcgg, A. A. Lindberg). American Chemical Society.
Washington DC. 1993. p 19 (ACS Simp Sw. 519).
T Feizi, C i m . Opii7. S / r . u ~ tBioi.
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1993. 3, 701
K. 0. Lloyd. Crinccr. B i d 1991. 2. 421: K.0 Lloyd. L J Old. C ' I I N ~ C
Re,\.
~.
1989. 4Y. 3445; K Ftikushiina. M Hiroto. P I Terasaki, A Wakisnki, H.
Togashi, D Chia. N. Suyama, Y. Fukushi. E. Nudelman, S Hakamori. i h d
1984. 44. 5279; S Hakamori, ihid 1985, 45.2405; M. P. Bevilaqua. R. M
Nelson, .I C h . I i i w s t . 1993. Y I , 379.
R. B. Merrifield. I . Singer. B Chait. A n d Bio</ioii. 1988. 174. 199.
M H. Caruthers. Sriefiw 1985. 2311, 281
J. M. J t.rechet in Poli.iiio--Siip/)ortrrl Rrwrionr iii Or,q(/riir
j'< i i r h r x s (Eds : P.
Hodge. D C. Sherrington). Wiley. Chichester, 1980. p. 1.
Reviews G.-J Boons. Rwcihcdrori 1996, 52, 1095: G . H. Veencman. S. Notcrmans, R M. 1. Liskamp. G A. van der Marel, J. H. van Boom, 7Ltrrr/ie(Jron
Lett. 1987, 28. 6695; L Y m . C. M. Taylor. R Goodnow, D . Kahne. J. An7.
C1'1rn7.So<. 1994. 116, 6953; S. 1'. Douglas, D. M. Whitfield. J. .I. Krepinsky,
ihid 1991, 113, 5095.
S. J. Danishefsky. M T. Bilodenu. Afigmr Ci'wii. 1996, 108, 1482; Aiigcw
C h i . hi/. Ed Efig/. 1996, 35, 1380.
S. J Danishefsky. K. t McCIure, J. T. Randolph, R. B. Ruggei-i. Sci~.,mw1993.
260, 1307; J Y. Roberge. X Beehe, S. J. Danishefsky. i h d 1995, 26Y. 202.
G . C Look, C. P. Holmes, J. P. Chinn. M A Gallop. .I 0r.g C%iw.1994. 59.
7588: k.. Albericio. M Pons. E. Pedroso. E Giralt. ibrd 1989. 54, 360; M
Mazure, B Calas. A. Cave. J. Parello. C. R A u i d S(i. Scr. 2 1986. 303, 553;
A. G. Ludwick. 1.W. Jelinski. D. Live. A. Kintanai-.J. J Dumais. J An?. C / i ~ i i ~ .
So(..1986, /OK. 6493, F Bardella. R Eritja. E. Pcdroso. E. Gii-alt. Bioorg. Med.
Ciioi?. Lei! 1993, 3. 2793; H . M. Eggenweiler. E Baycr. presented iit the
Fourth lntri-national Symposiuin on Solid-phase Synthesis, Edinburgh. 1995.
P. A Keifer. 1.Baltusis. I> M. Rice. A . A . Tymiac. 1 N . Shoolery. .I M ~ g n
Rm. A 1996. 119. 65: S S. Sarkar, R S Gargipati. 1. L Adams. P. A Keii'er,
I Am Cheix. S i x 1996, 118. 2305, W. 1.Pitch. G. Detre, C. P Holines, J. N.
Shoolery. P. A. Keifer, J Oig. Ciitw. 1994. 59. 7955; R. C. Anderson, M. A.
Jarema, M. J. Shapiro, J. P. Stokes. M. Ziliox. ihirl. 1995, 60, 2650.
H. Y Carr, E. M Parcell. PhJs. Kci,. 1954. Y4. 630; S. Meihoom, D. Gill, Rev.
Sci fnsri- 1958. 29, 6%
A Bax. S. Subrumanian, J Mugn. Rcson. 1986, 67, 565.
S. J. Danishefsky, R. L. Halcoinb, J Aiii. C ~ E I Soc.
I I 1989. 111. 6661
Novel Carbocyclic Ring Closure of
Hex-5-enop yr anosides
Sanjoy Kumar D a s , Jean-Maurice Mallet, and
Pierre S h y *
Carbohydrates have been used as starting inaterials for thc
synthesis of an extcnsive rangc of cnantiomerically pure noncarbohydrate natural products and relatcd substances.[]' The intramolecular ring closurc of carbohydrates to form carbocyclic
compounds is an attractive transformation. which offers direct
access to highly runctionalized cyclohexane derivatives. In this
[*] Prof P Sinay. Dr. S K. Das. Dr L M . Mallet
Departement de Chirnie. URA 1686
Ecole Norrnale Suptrieure
24 rue Lhomond
F-75231 Paris Cedex 05 (France)
Fax: Int. codc +(1) 44-32-3397
e-mail . sinay:u chimenc.ens.fr
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ring-closure reaction a carbanionic center (C6) usually attacks
the electrophilic carbonyl center (CI). An early example is the
Grosheintz- Fischcr synthesisr2]of deoxy nitroinositols fi-om
6-deox y-6-nitrohexoscs.
As predicted, the reaction of the known carbohydrate vinyl
acetal lr141
with four equivalents of triisobutylaluminum
(TIBAI) at 40 C resulted in the transposition of an oxygen
atom on thc ring with the exocyclic carbon atom (Scheme 4).
In 1979 Fcrrier reported the convenient conversion of an easily available hex-5-enopyranoside into a highly functionalized
cyclohexane derivative in the presence of mercury(l1) ~ h l o r i d c . ' ~ ~
Hydroxymercuration of the vinyl ether moicty of a hex-5enopyranosidc gives an unstable hemiacetal, which loses
1
2,79%
methanol to gcneratc a critical dicarbonyl interrnediatc
Scheme
4.
Typical
example
of
the
novel
carbohydrate
transposition.
(Schcme 1 ) . This species then undergoes an aldol-like intraniolecular cyclization to form a substituted cyclohcxane. Mechanistic and stereochemical ~ t u d i e s [as
~ 1well as modified reaction
The only isolatcd product of the reaction (79O/0) was the secconditions"] have been published. Highly functionalized cycloondary alcohol 2, which was formed by the subsequent stereohexanc derivativcs are of major significance for several groups
selective reduction of the carbonyl group by TIBAl. Starting
of natural products. This remarkable rearrangement--the Fermaterial (20%) was also rccovcred.
ricr-I1 reaction[61---has provided a practical route to a large
Although a detailed mechanism for the formation of 2 is still
wriety of bioactive substanccs such as aminocyclitols, pseudoa matter of speculation (Scheme 5), the reaction is presumably
sugars, and inositols.['] A basic feature of the Ferrier-I1 reaction
is the loss of alcohol, for example methanol (Scheme I ) , and
gcncration of an electrophilic aldehyde, which is necessary for
the aldol reaction.
L
- Rs%LoH
Schcmc 5. Probable incclianisin of the transposition Bn = b c n ~ y l
OR
Scheme I
initiated[l3] by the coordination of the aluminum atom of
TIBAl with the endocyclic enolic oxygen atom. This endo activation is followed by a ring opening step with the generation of the
zwitterionic aluminum enolate intermediate A. Assuming that A
retains its geometry on the time scale of the reaction, it may thcn
undergo direct cyclization through a twist form," 51 thus keeping
the anomeric stereochemical "memory". Alternatively, a rotation would give the intermediate B, which could then undergo
cyclization through a chair-like six-membered ring. In this case,
the electrostatic attraction bctwecn the positively charged oxygen and the negatively charged aluminum unit would hold the
enolate in proximity to the C - 0 TC bond (tight ion pair), which
nicely explains the obscrved stereochemical outcome. In both
cases the intramolecular aldol condensation ~ O C Sthrough the
favored['61 6-exo-trig process. The final reduction of the keto
group with TIBAl leads exclusively to the alcohol 2 by intramolecular hydrogen delivery from the less hindcrcd side.
Reaction of the vinyl acetal3 under the same reaction conditions provided the three secondary alcohols 4 in 70 %, 5 in 10 YO,
and 2 in 6 % yield (Scheme 6, physical and spectroscopic data
I'roposed mechanism for the Fcrricr-ll reaction [7].
We now rcport an alternative, direct conversion of hex-5cnopyranosides into highly functionalized cyclohexane derivatives without cleavage of the glycosidic bond. Thc discovery of
this novcl carbohydrate rearrangement is a result of a logical
cieduclion from two indcpendcnt facts: 1 ) Acyclic products of
thc selcctivc cleavage o f the ring carbon-oxygen bond of glycopyranosides have occasionally been observed upon treatment
uith suitablc elcctrophilic species (Scheme 2). 2) Hex-5-eno-
Sclienie 2. /Xi,activation
iii
glycosidc clcavagc
pyranosides are vinyl acetals wilh a vinyl ether subunit as
part o f an acctal moiety. Among the various reactions known
(or vinyl a c e t a l ~ , ~
the
' ~ triisobutylaluminum-assistcd rcductive rearrangement provides an elegant
cntry to substituted cyclobutancs,['"' cycloBnO
pro pane^,^' 'I tctrahydrofurans,[' 21 and tetraBno%OCH3
hydropyransr'31(Scheme 3).
jBU3A
OBn
PhMe,40°C
BnO-oCH,
B \ : m O C H 3
+
OHOBn
4 (70%)
3
PhMe, -78°C
FP
S c l i m e 3 St~rcocoiiti-olledPetasis syiithevis [13] of suhstitut-
ed
t c1i-3h y d rep! r:i iis
fl-oiii sii hst i t uted vinyl
‘ice t d l a
A'
Scheme 6. Application of the transposition to a 1-glucoside.
8'
OBn
5 (10%)
+
2(6yo)
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'Table 1 Physical and spectroscopic data for 2, 4. 5. 7-9. 11. 12. and 14 [a].
+
2 : [r];' = - 9 (< = O.X in CHCI,): ' H NMR (250 MHL. CDCI,)- 6 = 7 3 - 7 1 (m.
15H. arom. H), 4.85 4.6 (in. 6H, 3 -CH,Ph). 4.09 (t. 1 H. ./(2,?) = 9 3.
J(3.4) = 9 3 H7. H-3). 3.98 (dddd. I H. J(5,OH) = 9 5. .1(4,5) = 3.3, ./(5.6e) = 3 X.
J(5.6a)=2.0Hz.H~5).36(ddd.1H,J(1.2)=2.9.J(l.ha)=2.0.J(l.6e)=3.8Hz.
H-1),3.55(d, I H.OH).3.45(s. 3H,OMe),3.33(dd. 1 H. H-2).3.29(dd. 1 H. H-4).
2.2 ( d t . 1 H, J(6a.he) = 15.0 Hz, H-612). 1.25 (dt, 1 H.H-621)
9: Syrup. [r];" = 20 ( L = 0.9i n CHCI,). ' H NMR (250 MHL. CDCI,): 6 = 7 3
7.1 (20H. arom. H ) . 4.9-4.5 (m, 8H. 4 -CHiPh). 4 1 (1. 1 H. ./(2,3) = 9 2,
./(3.4) = 9.2 Hr. H-3). 4.0 (m.1 H. H-5). 3.9 (m.1 H, H-1). 3 7 (d. I H.
./(S.OH) = 9.4 Hz. OH). 3 32 (dd. 1 H. ./(1.2) = 2 8 Hz, H-2). 3.3 (dd. 1 H.
J(4,5)= 3 . 4 H z . H - 4 ) . 2 . 2 ( d t . l H . J ( l . 6 e ) = 3.9.J(5,6e)=39,.1(6a.6e)=150H1',
H-be). 1.3 (dt, I H. ,/(I.ha) = 2.0. .1(5.6a) = 2 0 H L . H-6a).
[TI?! = + 8 ( ( , = I 7 in CHCI,); ' H N M R (250MHz. CDCI,): 0 = 7 3
(15H. arom. H). 4 X - 4.55 (m.6H. 3 -CH,Ph). 4.05 (dddd. 1 H. ./(4,5) = 3.1,
J ( 5 , 6 a ) = 2.0, J ( 5 . 6 ~ =
) 4.4. J(5,OH) = 1.6 Hr. H-5). 3.73 ( t . 1 H. J(2.3) = 9.3,
J(3.4) = 9 3 Hz. H-3), 3.60 (ddd, I H. 4 1 . 2 ) = 9.1, J(l.6a) = 12.0. J(1,he) =
2.28 ( d t ,
4.4 HZ,H - l ) , 3.4 ( 5 . 3 H . OMc). 3.36(dd, 1 H, H-4), 3.30 (dd, 1 H.H-?),
1 H. J(6a.he) = 14.0 Hz. H-he), 1.2 (ddd, 1 H, H-ha).
5:Whitesolid.m.p. = 95 C , [ r ] i "= 3 5 ( r = 0.7inCHC13), 'HNMR(250MHz,
CDCI,).6=7.3-7.15(s.15H.arom.H).5.0-4.6(m.6H,3-CH,Ph),35
3.l(m,
5 H , ring protons), 3.4 (s. 3H. OMe), 2.29 (dt, 1 H. J ( l , h e ) = 4 0 . .1(5,6e) = 4.0.
J(6a,6e) = 12.0 Hz. H-he), 1.3 (ddd. 1 H,./(1,6a) = 12.0, J(5,6a) = 12.0 Hz. H-621).
7: White solid, m.p. =70 C; [z]iO= - 3 ( c = 0.95 in CHCI,); ' H NMR (250MHr.
CDCI,): 6 =7 2 (m. 20H. arom. H). 4 9 - 4 5 (m, XH, 4 -CH,Ph), 4.01 (m, 1 H,
H-5). 3.85 (ddd, 1 H. ./(l,2) = 9.4, J(1,ha) =11.3, J ( l . 6 ~ =
) 4.3 Hz. H-I), 3.75 (t,
1 H, ./(2,3) = 9.4. J(3.4) = 9 4 Hz. H-3), 3 4 (t, 1 H, H-2) 3.4 (dd. 1 H, H-4). 2.42 (bs,
OH), 2.28 (dt. 1 H. .1(5.6e) = 4.3, J(6a.he) =13.7 Hz, H-6e). 1.30 (dd, I H,
J(5.621) = 4.0 HL. H-68)
11:Whiresolid,m.p.=117'C.[2]:," = + 3(( = l i n C H C I , ) : ' H N M R ( ~ ~ O M H L ,
C,D,,)-6=7.3-69(m.15H.arom
H ) . 4 X 4.32(m.6H.3-CH,Pli).3.95(t.lH.
4: Syrup.
.J(l,2) = 8.7. J(2.3) = X.7 Hz, H-2). 3 73 (dd. 1 H. H-3). 3.55 (in, 1 H, H-5). 3.48
(ddd, 1 H. J(1.6a) = 10.7. J ( 1 . 6 ~ =
) 4.0 H L . H - I ) , 3.42 (m. I H. H-4). 3.2 (s. 3H,
OMeJ, 1.86 (ddd, I H. .1(5.6a) = 2 9 . .1(6a.6e) = l ? 5H7. H-6a), 1.72 (ddd, 1 H.
J(5,6e) = 4.0 Hz, H-6e).
+
12: White solid. m.p. = 97 C; [TI? = + 17 ( c = 0.8 in CHCI,): 'HNMK
(250MHz. CDCI,): 6 = 7 . 3 (m.1SH. arom. H). 5.09. 4.55 (2d. 2H. . / = 1 2 5 H z .
-CH,Ph).4.8(~,2H.-CH,Ph).4.70(ABq.2H.J=11.9
Hr:CHzPh).3.8S(dd.
1H.
43.4) = 2.4, J(4.5) = 1.5 Hz, H-4), 3.79 ( t . 1 H../(1,2) = 9.0..1(2.3) = 9.0 Hr. H-2).
3.47(ddd, 1H,.1(5.6a)=11.8../(5.6e)=5.0Hr,H-5),3.4(~.3H.OMe).3.32(dd.
1 H, H-3), 3.10 (ddd, I H . J(1.621) = 11.8. J ( 1 . 6 ~ )= 5.0 H/. H-I), 2.1 (s. 1 H, OH),
2.05 (ddd, J(6a,6e) = I 1 8 Hr. H-he). 1.67(ddd, 1 H. H-6a).
14: Syrup, [r]:,"= - 20 (c = 1.0 i n CHCI,), ' H N M R (250 MHL, CDCI,).
6 = 7 . 2 (in. I S H . arom. H). 4.7-4.4 (m. 6 H , 3 -CHzPli), 3.95 (dddd. I H .
J(4.5) = 4.0. .1(5.6a) = 8.0. J(5.6e) = 4 0,./(S.OH) = 9.6Hr. H-5). 3.75 (dd. I H.
J(2.3) = 6.0. J(3.4) = 2.7 Hz. H-3). 3.62 (dd. 1 H, J(1.2) =7.8 Hz. H-2). 3.62
(dd. 1 H. H-4). 3.50 (ddd. 1 H. , / ( 1 . 6 ~ =
) 8.0, ./(1,6;>) = 4.0 Hz, H-I). 3.32 ( s . 3H,
OMe), 2.35 (d, 1 H.OH). 2.01 (dt. 1 H, J(6a.6e) = 13.0 Hr, H-6e). 1 65 (ddd. 1 H.
H-6a).
8:Whitesolid.m.p. = I 2 1 C;[z]i"= + 2 5 ( ~ . = 0 . 9 5 i i i C H C I , J ; ' H N M R ( C D C I , .
250 MHr): 6 = 7 2 (m.ZOH, arom. H), 4.92-4.55 (m. XH,4 -CH,Ph). 3.55-3.34
(m.4H.ringprotons).3.23(t, IH..1=90Hz),2.2X(ddd, 1H, J = l l 5../=4.2.
./ = 4.2 Hz. H-6e). 1.37 (ddd, 1 H, ./(all) = 11.5 Hz, H-621).
[a] All compounds gave correct elemental analyses.
-
B;;,ooBn
are given in Table 1). Interestingly, 4
B~O=OBABU~A~
B n O D B n +
-E
+
L
:
and 5 (that is, 80% of the products) reBnO
BnO
OBn
PhMe, 40°C
tain the stereochemical information of
&OBn
OBn
OHoBnoBn
the anomeric center. Again, this reac6
7 81 %
8 (5%)
9 9%
tion may proceed through the ion pair
Scheme 7. An expedient synthesis of an optically active protected monodeoxygenated derivative of n?j.o-inositol.
A' o r the intermediate B'. Therefore, a
distinctive feature of this entry to highly
functionalized cyclohexanes is the retention of the anomeric stereochemical information in
the starting glucoside. This is in sharp contrast to
80% BnO
+
" L O C H
+
BnO
Bn&ocH
the Ferrier-I1 reaction, where the reaction inherently
BnO
OBn
OBn
OBn
requires an exo cleavage to eject the aglycon.
hocH,
,
In the same manner, the benzyl glucoside 6 was
10
11 20%
12 60%
converted into the alcohol 7 (83 %); isomers 8 (5%)
and 9 (9%) were also isolated as minor products.
Compound 7 has recently been prepared in racemic
A
H O F O OBn
C H ,
75% BnO
form from qo-inositol (Scheme 7)." 'I
+
Finally, thc same conditions were applied to vinyl
OCH
OH
OCH,
OBn
acetals 10 and 13 (Scheme8), which are derived
13
14
from methyl fi-D-galactopyranoside and methyl Z-DScheme 8. Application of the transposition to :I /~-galactomkand an r-mannoside
mannopyranoside, respectively (Scheme 9). In the
case of 10, the axially oriented benzyloxy group at C4 probably hinders reduction from the [j side; compound 12 is
the major product (60 Y O ) .
m T w R 1
%
&: ;B
B n O k R I 5
jR*: \B
Ri
BnO
In conclusion, we have developed a
R4 R2
R'
novel, stereoselective access to substitutR'
R'
ed cyclohexane derivatives, starting
1 R'=MeO; Ri=R3=H; R4=OBn
from hex-5-enopyranosides. A distinc3 R'=MeO; R2=R3=H; R4=OBn
6 R'=BnO; Rz==R3=H; R4=OBn
tive feature of the reaction is the reten13 R'-MeO; Ri=R4=H; R3=OBn
tion of the anomeric stereochemical information. An extension to disaccharides and ohgosaccharides is therefore
OCH b BzO
Bz&
OCH3&
c BzO
B&
OCH3 d BnO,
e
kOCH
BZQ
attractive. It would also provide an exOBz
OBZ
OBz
OBn
pedient and stereoselective entry to
10
pseudo disaccharides and oligosacchaScheme 9 Preparation ofthe hex~5~enopyranosides.
a) LiAIH,. AICI,. CH,CI,. ether, 30 C (XO'X); b) 12, Ph,l'.
rides,"81 which are
Of Poimidazole. toluene. 7 0 ' C (XO"/;,);c) DBU. T H E reflux (75%); d ) MeONa. MeOH, RT, e) BnBr. NaH. DMF.
tential biological interest." 91
RT (80%); Bz = benzoyl. DBU = 1,8-diarabicyclo[5 4 O]undec-7-ene
Bn01
-
,
-
-
,
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E.\-pcrinwnuil Scclion
A 1 M solution of ti-iisobutylaluminum in toluene ( I 8 inL. 1 8 mmol) was added to
I (700 mg, 0.45 nimol) in freshly distilled. dry tolucne (15 ml) at 0 - C The reaction
iiiixture w a r then stirred at 40 C for 6 h. After coinpletion of the reaction. exces?
triisobutylnluininiim was quenched with ice-cold water The reaction mixture was
filtered. and the organic phase separated. The water layer u'as extracted twice with
ethyl acetate The combined organic fractions were dried (MgSO,) and concentrated. and the residue subjected to flash chromatography (eluent. cyclohexanr ethyl
acetate 2,'l) to givc 2 as a syrup(158 mg. 79%)
Received: Scptcinber 23 l W 6 [Z95851E]
Ciei-man version A n p i i ' . ( ' h o i i . 1997. 109. 513- 516
Keywords: acetals
*
aluminum * carbohydrates . cyclohexane
Transition Metal Germylene Complexes as
Hydrogenation Catalysts: The Synthesis of a
Rare Bis(amino)germane**
Kyle E. Litz, J o h n E. Bender IV, Jeff W. Kampf, and
Mark M. Banaszak Holl"
Molecules in which germanium is bound to both hydrogen
and nitrogen are surprisingly rare."' Of the known examples,
namely, H,GeN, ,Iz1 H,GeNCS,r31H,GeNC0,[31(H,Gc),N,[~I
F,CN=GeH2,Is1 H,GeN=C=NGeH,,[61 and Ph,(H)GeNR, ,[71 the first three complexes contain pscudohalogen ligands
and thus resemble the well-established halogermancs. The
fourth example, (H,Ge),N, is widely known to exhibit delocalized rc bonding and enhanced Ge-N bond strength, whereas
Ph,(H)GeNR, is unstable and readily disproportionates to
Ph2CcH, and Ph2Ge(NR,),. Other than (H,Ge),N, we are not
aware of any aminogerniancs of stoichioinetry HGe(NR,), ,
H,Ge(NR,), , or H,GeNR, previously reported. In fact,
amino groups are commonly employed as leaving groups
when gerinancs arc formed by hydrogenation reactions, which
makes the easily accessible complexcs of general stoichiometry CI,Ge(NR,),. unsuitable as precursors to aniinogermancs.[81
Standard approaches for making aminogerinanes, which iiivolve reagents such as LiAlH, and NaBH,, typically
result in amine formation. Recently, we have synthesized
H,Gc[N(SiMe,),], (1) and H,Ge[CH(SiMe,),], (2) by both
stoichioinetric and catalytic routes using well-defined, threecoordinate, Group 10 metal germylene complexes of general
stoichiometry [ (R,P),MGeR'J .[91 The thrcc-coordinate catalysts are similar to compounds previously reported by Lappert
and co-workers.[lolIn addition, we have found that Nio complexes such as [Ni(cod),] (cod = 1,5-cyclooctadiene) can servc as
catalyst precursors, even in the absencc of phosphane.
The initially discovered routes to 1 and 2 made use of 3
and 4,as summarized in Scheme 1 : ' ' ' I Treatment of a benzene
[I] S. Hancssian. Acc C/xwi. Re?. 1979. 12. 159. B. Fraser-Reid, C. Anderson,
PIO~
c'/iN77. Orx. Nut. SVZ//I.M<,I/iod\ 1980, 39. 1 ; A. VtIsS~la.M d . S ~ ~ i t h .
Mctiiodr 1980, 2. 173; S Hanessian. 7i>tril . ? w ~ r / i r . s i s of' Nrrfurtd P r u d i ~ t s ,The
Chiroii Ap/)rouch. Peryamon. Oxford. 1983.
121 J. M Groshcintz, H. 0. L. Fischer, .I ,4171 (.hem S i x . 1948, 70, 1479; T. Iida.
M. Funabashi, J Yoshimura, Bull. Clirni. So<. ./pn. 1973, 46, 3203; J. Kovac,
H . H . Bacr, Cnrhohj-rlr Re.\. 1975. 45, 161. and references therein; review:
H. H. Baer, Ads Curhohj.i/r. C / w n . Biodirw. 1969, 24, 67
[3] K.J. Ferrier. .1. Chiwi. SOC.Perkrii Ti.ans 1 1979. 1455.
[4] K.Yamanchi, T 'lei-achi, T. Eguchi, K. Kakinuina, Te/rrilie(/ron1994,50,4125;
R . Blattncr. R. J Ferriei-. S. R Haincs, .I Chrni. Soc. I ' r v k i i i Ti.ans. 1 1985,
2413. A. S. Machado. D Dubi-euil. J Cleophax. S. D. Gcro, N. F.Thomas.
(iirhohrdr. Rcs. 1992, 233. C S , P Laszlo. A. Dudon. J . Cui./w/rrdr. C/rm.
1992. / / . 587
[ 5 ] A. S . Miichado, A. Olesker, G. Lukacs, Curhohidi- Re< 1985, 13.5. 231; N.
Cliida. M Ohtsuka. K Ogura, S. Ogawa. BE///.
Chcni. Soc J p i 1991, 64. 21 18:
S Adam, 7iJti-rrlicth-on Lett 1996. 37, 649
[6] For a description of Fei-i-ier-lreaction5 see R. J. Fcrrier. A d v Ctri-holij d r C%em
1965. 20. 67.
[7] Review' K J Ferricr, S. Middleton, Choii. Rcv. 1993. 93. 2779
[XI C. B. Post. M. Karplus. .I A m Choii. Soc 1986. /OK, 1317, Y Guindon, P. C.
Anderson. 7i~friilictlroriLrtt. 1987, 28, 24x5; D. R McPhaiI. J. R. Lee, B.
Fi-a\ri--Reid. .I. Aiw. Cliivn. So<.1992, 114. 1905
[9] H. Frauenrath. Xmfhr.sir 1989, 721
[It)] K.Meiiicagli, C:. Malanga, L. Lardicci, .I Org. Chcrn. 1982, 47. 2288.
[I I ] K Meniciigli. C. Malanga. M . Guidi. L. Lardicci. 7i,trohri/roii 1987. 43. 171.
R. Municagli. C. Malangd. M. Dell'lnnocenti. L. Lardicci. J Org Cheii~1987,
52, 5700
1121 K.A. Petasis. S. 1' Lu. ./ Am. C/iom
Snc 1995. 117. 6394.
1131 h.A. Petcisis. S P Lu. 7i~trir/1cr/ro11
Lrti 1996. -1'7. 141.
excess PEt3
[I41 K. Sakairi. H Kuruhara, 7 ? / r i h r h i i
L<,/t. 1982. 23. 5327.
[IS1 T. Timori. H . Takahashi, S. Ikcgami,
7i~trrilictlroiiLei!. 1996. 37, 649, see ref'.
Et3PI,
HZ
Et3P, ,H
[4] of this cominunication.
Pt --Ge[N(SiMe3)z]2 @
,Ptbe:N(SlMe3h
[I61 .I. E. Baldwin. M J Lush. 7i~rrahrdron
Etp'
-H2
Et3P
3
1982. 19.2939.
N(SiMe,h
[ 171 J. Yu. J. B. Spencer. .I Org Ckm7 1996.
61,3234
[ I X ] S Ogawa. S -1. Sasaki, H Tsunoda.
Crrrhohi-h- Re\ 1995, 274. 183, and
references therein.
Et,Pi,
H2Ge[N(SiMe31212 +
'Pt --Ge[CH(SiMe,t,
[I91 J F..' Duiis. K. Bock. S Opiwa. Cbi-hii/i)ili R i d \ 1994. 252. 1.
Et3P.
T
k
l2
5
1
Scheme 1. Synthetic route to 1
[*I
[**I
Prof. M. M . Banaczdk Holl. K. k.Litr, Dr. J. W. Kampf
Chemistry Department, University of Michigan
Ann Arbor. MI 4x109-1055 [USA)
Fax: Int. code +(313)763-2307
e-mail' mbaiia%i:ir umich.edu
J. E. Bender 1V
Chemistry Department. Bi-owii University
Providence, R1 02912 (USA)
'Theauthors thank AIf;i-Aesai- for agenerous loan of KIIPtCl,] and the University of Michigan for financial support of this work. J. E. B. thanks the N S t for
a graduate fcllowsliip.
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