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Conversion of Glycosyl Azides via N-Bromoglycosylimines to Aldononitriles.

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mosilcates) has already been shown, for example, with "boron/
MFI-zeolite"."
Received, October- 20. 1993 [Z 6436 IE]
German version: Angcw. Cheni. 1994, 106, 791
z.
111 H. B ; ~ ~ ~ .4110rg.
~ - . A//,.. c / i e f ] i . 1965. 337. 183-190.
[2] H . Batier. 7 Aiiorg. A//g. Chm7. 1966. 345. 225-312.
[3] P. R,imamoorth?. T. J. Rockett. J h i . Carurn. Soc. 1974. 57, 5 0 - 5 0 2 .
[4] J. Liebcrtr. S. Stiihr. 2. Kri.r/o//ogv. 1982. 160. 135-137.
(51 A Kulinont, P. Tarte. .I. Sold slut^ Chen7. 1988. 75, 244-250.
[h] A . A Voi-onkov. Yu. A. Pyatenko. Kric.fo//ogrufira1967. 12, 258-265: SOL'.
/'/it,>
C ' r ~ ~ . \ / u / / o1967.
~ r . I?, 214-220.
[7] G . F.. K.Schulre. 2. P/ir.s. Chiwi. 1934. 8 2 4 . 215- 240.
[XI J. D. M;ickcnric. W. L. Koth. R. H. Wentorl: Actu Crjwollogr. 1959. 12. 79.
[Y] F. Dachille. 1.. S. Dent Glasser. Acia Crysdiogr.. 1959, 12, 820-821.
[lo] ; i j C'a[UPO,] (Sr[BP05]j: Space group P3,21: u = 667.99(2) (684.88(1)). " =
661.11(3)(681.59(3))pm;Z= 3 : ~ ~ =~3.53(3.19)gcm-3;Stoediffractome, ' ~
ter (1.1 1.1. I7"sition-sensittve detector. Cuk, radiation: 2 0 range,'step width 10
to 10; 0.07 (18 to 105 i0.02 ): number of measurements used for refineniciit- 11.% (1006): structural refinement using the Rietveld method 1121 (isotcpic relation to stillwellite [6]: number of refined profile parameters: 16 (15):
numhcr DI' refined structural parameters. I6 (16); R,, = 0.079 (0.111. K ( / ,
/&/) = 0.073 (0.077). (b) Further details of the crystal structure investigation
ma? bc ob(,iined from the Fachinformntions7entrum Karlsruhe. D-76344 Eggen\teli~-Lcopoldshalen( F R G ) on quoting the depository number CSD57927. the niinies of the authors, and the journal citation.
[ l l ] B:i,[BP,C),,] S p a c e g o u p f b c a ; u = 2221.1(8], h=1429.6(6). c =710.(4)pm;
, = 4 . 1 7 g ~ m - ~1328
: independent observedreflections(I 2 2 0 ( / ) ) ;
I 1 0 0 diffrnctometei-. 2 0 range from 5 to 60": Mo,, radiation:
R = 0 (175. residual electron density +3.2/-4.9 e - l o - " pm - 3 [lob].
(121 H, \.I Rietveld. f Appl. C>j.,>tu//o,yr.1969. 2~65- 71.
[ I ? ] Nomeiicleittire Liccording to F. Liebau. Sti I N rural ChcniOtrv qf Si/icates,
Springer. Berlin, 1985.
(141 M Wiehckc. C C . Freyhardt. J. Felsche. G . Engelhardt, Z . Nuturforsch. B. in
pt-CIE
[Is] M. T. Averbuch-Pouchot, J. Solid Stafc Ch~777.1993. 102. 93-99.
[I61 M.: 1: .9.
Harrison. 7 M. Nenoff. T. E. Gier. G. D. Stucky. Inoi.8. C/7em. 1993,
32. 3137 -2441
[I71 W. I: A Hxi-rison. T. E Gicr. G. D. Stucky, Angcm~.Chmi. 1993. 105. 788 790:
C'/iwn. Iiir. GI. Dig/. 1993. 32, 724-726.
ntilli. S. 1. Zones in Synlliesis of Micropurous mute rid^: Vo/. 1 , M o l ~ c 'c\ (Eds : M. L. Occelli. H. E. Robson). Van Nostrand Reinhold. New
Yorh. 1992. p 373.
[I91 Nore addzd iii proof A recent. more extensive literature search revealed the
~ ~ r t i c t i i ideterminations
-c
of the minerals liincburgite (Mg,(H,O),[B,(OH),1 and seamanite (Mn,(OH),[B(OH),][PO,1). Luneburgite contains
diiiicric l e t r h x h l units [BPO-]'. (P. K. S. Gupra. G. H. Swikart. R. Dimitrij c \ i c . \I. 8. Hossain. A717cr. M h i e r d 1991. 76, 1400 1407)). whereas the cryst:iI \tructure of seamanite contains isolated BO, and PO, tetrahedra (P. B.
Moore. S Ghose. Am11~.. M / n ~ r u l 1971,
.
56. 1527- 1538. .
Conversion of Glycosyl Azides via
N-Bromoglycosylimines to Aldononitriles
more detail. Any synthetic application, however, must take their
hydrolytic lability and low thermal stability into account. We
report here on a metal-triggered reaction which converts these
sensitive compounds to substituted aldononitriles.
The extraordinary reactivity of metal-graphite reagents makes
them suitable for inducing many transformations under neutral
conditions in aprotic media at low reaction temperatures; therefore, they can be applied nicely to hydrolytically labile subs t r a t e ~ . ' ~Furthermore,
]
they are compatible with a variety of
functional groups and can thus also be applied to complex natural
products.[41Deoxyhalo sugars, for example, on treatment with
either C,K or Zn/Ag-graphite are prone to reductive eliminations, resulting in the smooth ring opening of the carbohydrate
precursors.[s1 N-bromoglycosylimines may also undergo such
dealkoxyhalogenations. if clean N-metalation can be achieved
(Scheme 1).
RX
IN n
2
Scheme 1. Successive reaction ofglycosyl aatdes with NBSand metal-graphite(M*)
(schematic representation). The structural analogy between %bromoglycosyliminea 1 and (Z)-hydroxyiminoglyconolactones2 is evident.
The reaction of 2,3.4,6-tetra-0-acetyl-fl-~-g~ucopyranosy~
azide 3arb1 with NBS and azobisisobutyronitrile (AIBN) in
CCI, according to the literature procedure['] and the subsequent
treatment of the crude bromoimine derivative 4 a with an excess
of Zn/Ag-graphite in THF, however. did not lead to a clean
transformation. Since the N M R study of the crude product
indicated the presence of several aldononitrile derivatives, the
mixture was acetylated (Ac,O/pyridine) , affording penta-0acetylglucononitrile 617]in 71 % isolated yield (Scheme 2). Since
partial migration of the acetyl groups in the intermediate ringopened zinc alcoholate 5 a (M = ZnBr) apparently accounted for
the observed mixture, we chose azides stable to basic conditions,
such as 3 b and 9 (Scheme 3),['] as substrates. In fact, after
Max-Plnnck-lnstitut fur Kohlenforschung
Kaircr-Wilhclm-Platz I , D-45470 Mii1heirn;Rulir (FRGj
Tclelcix: Int. code (208)306-2980
+
Dr. .1-P Praly
Universite Claude Bernard Lyon 1
Leborntoire dc Chimie Orgiinique Associe a u CNRS. ESCIL
43. Boulev,ird du 11 Novembrc 1918- F-69612 Villeurbanne (France)
r
OR'
N-bromosuccinimide (NBS) reacts with /Gglycosyl azides to
afford N-bromoglycosylimines 1 in good yield,['] the chemistry
of which is completely unexplored. Their similarity with (Z)-hydroxyiminoglyconolactones 2, which have been used, for example. for the synthesis of spiro sugars, carbohydrate derived
oxazoles, glycosylidene carbenes, and ring-expanded structures.['] makes it worthwhile to explore the reactivity of 1 in
U n i \ -Doz. Dr. A. Furstner
>
R
OR
Alois Fiirstner * and Jean-Pierre Praly *
[*I
O
3a, R'
L
AC
3b, R' = Me
1
OR'
~
'
0
%R'O
CZN
OR'
5a, R ' = A c
5b, R = M e
RX
/
OR'
4a, R ' = A C
4b, R' =Me
R'O
R'O
RO
' +CN
RO
R'O
6, R = R ' = A c
7 , R = H , R'=Me
8, R = C(S)SMe, R' = Me
Scheme 2. Reactions according to Scheme 1 in the glucose series: M*
graphite or 2C,K (see Table I).
=
2n:Ag-
COMMUNICATIONS
Table 2. Physical and analytical data of 3 b . 6-8. and l 2 a - d
3b: Syrup: [a];" = 22 (c = 2 in CHCI,); 1R: i. = ZllOcm-' (N,): ' H N M R
(200 MHz, C6D6): 6 = 2.91 (t. J(2.3) = 8.5. 1 H, H-2). 3.06 (t, J(3.4) = 8.X, I H,
H-3). 3.06 (m, J(5.6) =1.5, J ( 5 , 6 ' ) = 3.8, 1 H, H-5). 3.14 ( s , 3H. OMe), 3.22 (t.
~
J(4,5)=9.5.1H,H-4).3.38,3.40(s,each3H,OMe),3.41(m,2H,H-6,6),3.50(s
L
9
10
3H, OMe).4.12(d.J(1.2) = 8.4,l H, H-I); 13CNMR(50 MHr,C,D,): 6 = 59.17.
60.25. 60.37. 60.75. 71.27. 77.49. 79.29. 83.90. 87.30. 90.13.
6 : M.p. 83-85 C (ref. 171: 82-84 C); [a];' = +46.9 (c = 0.6 in CH,C12) (ref. [7].
t 4 7 . 3 ) ; 'H NMR(300 MHz. CDCI,): 6 = 5.56(dd,J(3,4) = 2.6,5(4,5) = 8.3.1 H,
H-4),5.48(d,J(2,3)=6.3.1H.H-2).5.37(dd,lH.H-3),5.ll(ddd,J(5.6)=2.9,
J ( 5 . 6 ' ) ~5.1H.H-5),4.08,4.22(dAB.J(6.6')~12.5.2H.H-6,6).2.14,2.12,2.11,
2.03. 2.02 (s, each 3 H , MeCOO); ' , C N M R (75 MHz, CDCI,): 6 = 170.41 (s).
169.60 (s), 169.46 (s). 169.41 (s), 168.24 (s), 114.11 (s). 68.22 (d). 67.19 (d), 67.10
(d). 61.61 (t), 58.90 (d), 20.62 (4). 20.31 (q), 20.05 (q).
12a, R = H
12b, R=CHzPh
I~c
R =,
C(0)Ph
12d, R = SiMePhz
11
Scheme 3. One-pot conversion of mannofuranosyl azide 9 to protected mannononitriles 12. M* = Zn:Ag-graphite o r 2C,K (see Table 1).
conversion to the corresponding bromoimines, both nicely gave
the respective nitriles in good yield upon reaction with either
Zn/Ag-graphite or C,K (Table 1 ) . The use of C,K provided the
additional advantage that the intermediate potassium alcoholates 5 b and 11 (M = K) may be trapped in situ with electrophiles, thus affording differently protected aldononitriles in
one high-yielding step (Table 1). The synthetic potential of these
highly functionalized sugar derivatives previously prepared by
multistep approaches has been outlined recently.['01
Tahle 1 Preparation of aldononitriles from glycosyl azides
Substrate
M*-Graphite
RX
Product (Yield)
3a
3b
9
9
Zn:Ag
C8K
ZwAg
C8K
C,K
CaK
C,K
Ac,O [a]
CS,:'MeI
- lhl
- [hl
C,H,CH,Br
C,H,COCI
Ph,MeSiCI
6 (71 "A)
7 (10%). 8 (62%)
12a (87%)
12a (90%)
12b (76%)
1 2 (80%)
~
12d (86%)
9
9
9
[a] Acetylation using Ac,O ( 5 equiv) in pyridine. [b] Moisture of solvents used for
workup as proton source.
7 : Syrup; [a]:' = +62 (c = 0.2 in CH,CI,); ' H N M R (300 MHz, CDCI,): 6 = 4.37
(d. J(2.3) = 6.8. 1 H. H-2). 3.88 (dt. .I = 4. 8. 1 H, H-5). 3.79 (dd. J = 2.6. 7, 1 H),
3.45-3.62 ( m . 4 H ) , 3.57. 3 54. 3.47, 3.38 (s.each 3H, OMe); I 3 C N M R (75 MHz.
CDCI,): 6 =116.87(s),XO.98(d), 79.85(d), 73.22(t).72.19(d),69.50(d).61.29(q).
60.51 (9). 59.19 (4). 58.84 (q).
(c = 4.9 in CH,CI,): ' H N M R (300 MHz, CDCI,): S =
5.80(dt J = 3.6.6.1 H,H-5).4.31 ( d , J ( 2 , 3 ) =7. lH.H-2),3.96(dd.J= 2.6. 7 , l H .
H-3). 3.80, 3 63 (dAB. J(5.6) = 2.6. J(5,h') = 3.8, J ( 6 , 6 ) =11.6. 2H. H-6.6'). 3 48
(2s. m, 7H. H-4. 2-OMe). 3.40. 3.30 (s, each 3 H . OMe). 2.51 (s, 3H. C(S)SMe);
I 3 C N M R (75 MHz. CDCI,): 6 = 215.22 (s). 116.37 (s), 80.77 (d), 80.61 (d), 78.25
(d), 71.73 (d), 69.68 (t). 61.0X (q), 61.02 (q), 59.17 (4). 58.74 (4). 19.28 (q).
8: Syrup; [XI,? = +10.4
12a: M.p. 9 7 - 9 8 - t : b];" = f 6 2 . 4 (c=1.2 in CH2CI,); ' H N M R (300MHz,
C D C l d 6 = 4.81 (d. J(2.3) = 5. I H, H-2). 4.15 (ddd, J(3,4) = J(4,S) = 8.2, J(4,
-OH)=1.5,lH,H-4).4.07(dd.IH,H-3),3.78-3.95(m,3H.H-5.H-6,6),3.21(
1 H. OH). 1.53. 1.39. 1.34. 1.27 ( 5 . each 3 H , Me): ' V N M R (75 MHz, CDCI,):
6=117.12(~).111.53(~),110.43(~),79.50(d),75.69(d),72.55(d),68.02(t),66.37
(d), 26.97 (q), 25.92 (2q). 28.16 (4).
12b. M.p. 74 76 C ; [a];" = +71.5 (c =1.2 in CH,CI,): ' H N M R (300 MHz, CDCIJ: d =7.35-7.39 (m. 5H. -Ph). 5.00.4.70(AB. J(AB) ~ 1 1 . 42H,
, CH,Ph). 4.89
(d.J(2.3)=4.9,1H3H-2).4.24(dd.J(3.4) =8.5,1H,H-3),4.18(dd.J(4,5)= 6.5,
1 H. H-4), 3.98 (ddd, J(5.6) = J ( 5 . 6 ) = 8.7, 1 H. H-S), 3.82 (dd, J ( 6 , 6 ' ) = 8.7. 1 H.
H-6). 3.74 (dd, l H , H-6'). 1 68. 1.46, 1.45. 1 34 (s. each 3H. Me); Y N M R
(75 MHz. CDCI,): 6 =138.05 (s). 128.61 (d), 128.42 (d). 128.29 (d), 128.17 (d),
117.55(~).111.65(s).110.72(~).81.08(d),79.97(d).75.42(d).74.75(d),68.50(t).
67.04 (d), 27.26 (q), 26.22 (q). 25.90 (q), 25.44 (9).
12c: M.p. 131-132-C; [TI;'
= +20.8 (c = 0.3 in CH2CI,); ' H N M R (300 MHz.
CDCl,):6 =7.45-X.OY(in,5H,Ph).5.57(dd,J(3.4)
= J ( 4 . 5 ) = 8.3.1 H.H-4),4.96
(d,J(2,3)=5.2,lH,H-2).4.48(dd,lH,H-3).4.11-4.28(m,2H.H-6,6').4.02(dd,
J ( 5 , 6 ) = J ( 5 . 6 ) = 8.6.1 H.H-51, 1.59. 1.50,1.40,1.38(s, each3H. Me); I 3 C N M R
(75 MHz, CDCI,): 6 =165.49 (s). 133.61 (d), 130.18 (d), 129.75 (s), 128.70 (d).
116.92 (s). 112.18 (s), 110.95 (s). 77.79 (d). 7 5 04 (d). 72.67 (d). 67.89 (t). 66.48 (d).
27.10 (q). 26.26 (2 q ) , 25.74 (q).
12d: Syrup [r]:" = +42.2 (c = 0.7 in CHJI,);
'H NMR (300 MHz, CDCI,):
6 =7.41-7.69 (in. 10H, Ph): 4.87 (d, J(2.3) = 3.3. 1 H, H-2), 4.08-4.21 (m. 4 H ) ,
3,72(dd,1H),1.58.1.45.1.38.1.25(s,edch3H,Me):'~CNMR(75MH~,CDC1,)~
6 =138.02 (s). 137.98 (7). 134.60 (d). 134.50 (d), 134.14 (d). 130.16 (d). 129.91 (d).
128.05 (d), 127.64 (d), 117 32 (s), 111.11 (s). 110.66 (s). 80.32 (d), 76.59 (d), 75.04
(d). 6X 86 (t), 66.64 (d). 27.07 (4). 25.76 (2 q). 25.56 (q). -2.24 (1 9).
Attempts to cyclize xanthate 8, obtained by quenching the
potassium alcoholate 5 b (M = K ) with CS, followed by alkylation with methyl iodide, under radical conditions f d e d . [ ' ' I
In summary, we describe the first transformations of sensitive
N-bromoglycosylimines. Upon treatment with metal-graphite
reagents these carbohydrate derivatives can be reductively ringopened to aldononitriles, with an additional option for in situ
derivatization if C,K is used as the reducing agent. The reaction
sequence constitutes not only a high-yielding approach to enantiomerically pure open-chain building blocks from sugars, but
also proves for the first time that dealkoxyhalogenations can
occur along (hetero) double-bond systems.
Esperinlenral Procedtiue
1 2 c ' To a solution of 2.3:5,6-di-0-isopropylidene-/(-D-mannofuranosyl aLide 9
(300 mg. 1.05 mmol) [XI in CCI, (40 mL) was added NBS (393 mg, 2.21 mmol) and
AIBN (10 mg) The mixture was stirred at room temperature until TLC showed
complete conversion of the substrate and the appearance of a faint brown color in
the reaction medium indicated the end of the conversion (2-3 h). The insoluble
residues were filtered off. rinsed with CCI, (10 mL), the solvent removed in vacuo
at <20 'C (bath temperature). and the residue coevaporated twice with T H F (3 mL
752
I'
VCH Vrrlu~c~~~sclI.\c/iu/t
m h H , 0-69451 Weinlierin, 1994
each) to ensure complete removal of the CCI, from the syrup. The crude 10 thus
obtained was dissolved in T H F (3 mL) and added to a suspension of C,K (426 mg,
3.15 mmol) [5. 91 in T H F (20mL) under argon. TLC showed rapid conversion
( < 5 min) to a more polar compound. After addition of henzoyl chloride (300 nig.
2.13 mmol) in T H F ( 1 mL), the reaction mixture was stirred for 1 h a t room temperature. filtered, the solvent evaporated, and the residue purified by flash chromatography affording 12c as colorless crystals (304 mg, 80%).
Received: October 28. 1993 [Z6460IE]
German version: AnRew. Chem. 1994. 106, 779
[l] a) J.-P. Praly. C. Di Stefano. L. Somsak, G. Descotes, J. Chg.m. Soc. Cherii.
Cornmuri. 1992. 200-201; b) J.-P. Praly, D. Senni. R. Faure, unpublished
results.
[2] a) D. Beer, A. Vasella, Hdi,. Chin,. Acfu 1985, 68, 2254-2274; h) E. Bozo, A.
Vasella, ;hid.1992, 75, 2613-2633; c) A. Vasella, Pure Appl. Chem. 1991, 63.
507-518, d) M. Yokoyama, K . Sujino, M. Irk. N. Yamdzaki, T. Hiyama, N.
Ydmada. H. Togo. L. Chern. Soc. Perkin Trans. f 1991. 2801-2809: e) M.
Yokoyama. M. Irie, K. Sujino. T. Kagemoto. H Togo. M. Funahashi, ibiil.
1992, 2127-2134.
[3] A. Fiirstner, Angew. Cl~eni.1993. 10s. 171-197: Angfw. Chrm. Int. Ed. Engl.
1993. 32. 164-189.
0570-O~33~Y4j0707-0752
S 10.0Ot.25:0
A n g i w Chein. Inr. Ed. Engl. 1994, 33, N o . 7
COMMUNICATIONS
a) A . Ftirrtner. J. Baumgartner. Telruhedron. 1993. 4Y, 8541-8560; b) R. E.
Ireland. T. K . Highsmith, L. D. Gegnas, J. L. Gleason, J. Org. Chern. 1992. 57,
5071 5073.
a) A. Fiirstner. H. Weidmann, J. Org. Chetn. 1989. 54. 2307-2311; b) A.
Fiirstiier. D. N . Jumbam. J. Teslic. H. Weidmann. rhirl. 1991, 56, 2213- 2217;
c ) A. Fiirstner. 7Lrruh~dronL e f l . 1990. 31. 3735-3738.
H . Pnulsen. Z. Gyorgydeak. M. Friedmann, Chrm. Ber. 1974. 107. 1568- 1578.
R. Kuhn. J. C. Jochims, Chem. Ber. 1960. Y3- 1047-1052.
Compound 9: W. Schorkhuber. E. Zbiral, Liebigs Ann. Chcwn. 1980. 14551469. Compound 3 b was prepared by Zemplen deacetylation of 3a. followed
by methylation (NaHiMel in dimethylformamide). for physical data see
Table 2.
Similar trapping experiments were successfully used in glycal syntheses, see:
a ) A. Fiirstner. H. Weidmann. J. Curhohjdr. Chern. 1988, 7. 773 783; b) A.
Fiirsliicr. L;rihi,o.s Ann. C/7en?.1993, 1211 -1217.
P. Erinert. A. Vasella. H d v . ChOn. Acru 1991. 74, 2043-2053.
Successful cyclirations by the addition of carbon-centered radicals onto nii ) D. L. J Clive. P. L. Beaulieu. L. Set, J. Org Chein.. 1984, 49, 13131314. b) J. K Dickson. R. Tsang, J. M . Llera. B. Fraser-Reid, i h d . 1989, 34,
5350 5356; c ) H. Pak, .I.
K . Dickson. B. Fraser-Reid. J. Am. Chen?. Sor.. 1989,
54. 5357 -5364; d ) R. A. Alonso. C. S. Burgey, B. V. Rao, G. D. Vite, R.
Vollerthun. M . A Zottola. B. Fraser-Reid, ;hid 1993. 11s. 6666- 6672; similar
failures c ) N. S. Smpkins, S . Stokes. A. J. Whittle. J. Cheni. SOC.Perkin Trun.s.
1 1992. 2471 2477; f) J. Marco-Contelles, C. Poruelo. M. L. Jimeno, L. Martinet. A. Martinez-Grau, J Org. Chew. 1992. 57, 2625-2631: g) B. W. A.
Yeung. 1. L. M . Contelles. B. Fraser-Reid. J Chem. SOC.Chrni. Convnun. 1989,
1160 1161.
~
Determination of the Relative Configuration by
Distance Geometry Calculations with ProtonProton Distances from NOESY Spectra **
urations of molecules that may be flexible. To answer this question we conducted "NOE-restrained" molecular dynamics calculations with heavily weighted experimental distances.[*' The
problem of the parametrization of the force field prevents the
general application of this approach. Since suitable parameters
are not available for many interesting systems such as polar
organometallic compounds, alternative procedures had to be
developed. The best approach appeared to be the application of
as many actual measurable quantities, in other words H-H distances, as possible.
In principle conformations can be determined from distance
data by distance geometry (DG) calculation^,[^^ 41 a procedure
used for the N M R spectroscopic structure determination of biopolymers.[31The absolute configuration of a stereogenic center
is determined by the sign of the "chiral volume" ( Vc)['I taken up
by the atoms bound to this chiral center. Typically a constant
value is maintained for the chiral volume in the calculations to
ensure the stereochemical integrity of the stereogenic center under consideration. If this chiral restraint is removed, the sense of
chirality can be inverted and a new conformational space is
opened up, within which a conformation can be found that
optimally fits the distances obtained from the NOESY data.
This method was applied for the assignment of diastereotopic
protons in proteins,[6' and we have demonstrated its suitability
for the determination of the configuration of a model comp ~ u n d . ~ Since
']
the stereogenic centers of interest were in a section of the molecule that could be determined quite well from
NOES (bridgehead positions), we wondered if this method was
generally applicable. To find out more about the potential of
DG calculations for the determination of relative configurations
we chose the much more flexible bisoxazolidine 1.r8]
Michael Reggelin,* Matthias Kock,
Kilian Conde-Frieboes, and Dale Mierke
Investigations of the structures of reactive organometallic compounds such as lithiated or titanated 2-alkenylsulfo~imides~~~
are
quite difficult. Studies of these species under the conditions required for their reaction, in other words at low temperatures and
in solution, are particularly problematic. Here N M R spectroscopy is the method of choice, since in principle the reaction
dynamics (e.g. conformational flexibility. configurational behavior) of the metalated intermediates can be examined, which
may aid in the interpretation of the stereochemical outcome of
the reaction.['] Often when no other method is available, only
the relationship between the configuration of the metalated intermediates and the stereochemistry of the products of a stereoselective organometallic reaction can provide information on the
stereochemistry of these intermediates. Thus, the development of
a method independent of postulated models of transition states
(e.g. Zimmerman-Traxler model) would be very valuable.
The obvious question is how N M R data (H-H distances,
coupling constants) can be used to determine the relative config[*I Dr. M . Reggelin. Dr. M. Kock, Dr. K . Conde-Frieboes
l i i s t i t u t fur Organische Chemie der Universitit
Maric-Curie-Strasse 11. D-60439 Frankfurt am Main ( F R G )
Tclefar. Int. code + (69)5800-9128
Dr. L). F Mirrke[+'
Orgaiiisch-chemisches lnstitut der Technischen Universitit Munchen
Lichtenhergstrasse 4. D-X5747 Garching ( F R G )
['I Precenl address:
Department of Chemistry. Clark University
Worcester. MA 01610 (USA)
[**I Thia work was supported by the Deutsche Forschungsgemeinschaft and the
Fonds der Cheinischen lndustrie (Habilitation fellowship for M. R. and postdoctoral fellowship for M. K . ) . We thank Prof. Dr. C. Griesinger and Prof. Dr.
Fl. Kesslei- for their generous support.
A i w ' i I Chcni. f n c . Ed. Eiig/. 1994. 33. N o . 7
-CI
L
Cl
1
In addition to the known stereogenic centers in the norpseudoephedrin section of the molecule, 1 has six additional centers
with unknown configurations. Two-dimensional N M R spectroscopy was used for the assignment of all of the protons in 1.['1
The analysis began with the differentiation of the two quasisymmetric halves of the molecule. The OH-bearing carbon atom
(C-11) was easy to identify, because it does not give rise to a
cross peak in the proton-detected H - C correlation spectrum
(HMQC1'O1).This atom has a heteronuclear long-range correlation (3JC,H)
with the proton at C-16 (HMBC["I), which was
used to identify the halves of the molecule. The 'H signals within
each half were assigned based on DQF-COSY and TOCSY
experiments.[121The arene protons were assigned with a selective
HMBC experiment (excitation with a 270" Gaussian pulse[i31).
Seven 400 MHz NOESY spectra were recorded for the determi-
ic? VCH V r r l u ~ . ~ ~ e s e / / . rnihH,
~ l i a / fD-6Y45l Weinheim, 1994
OS70-0833iY4~0707-0753
$ 10.00
+ 25.'0
153
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bromoglycosylimines, aldononitriles, glycosyl, azide, via, conversion
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