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Reversal of the Refioselectivity in the Zirconocene-induced Coupling of a ketone with Isoprene.

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tients suffering from cystic fibrosis"]. Using the trichloroacetimidate method developed previously by us121,we
have now synthesized 8 from the disaccharide building
blocks 4 and 6 using a method which dispenses with halogenoses and heavy metal salts131.
Upon treatment with trichloroacetonitrile and sodium
hydride, N-phthaloyl-3,4,6-tri-0-acetylglucosamine141
afforded the O-(o-glycosyl) trichloroacetimidate 1 (76%,
m. p. = 146°C); the galactose derivative 2 with unprotected
3-OH group ([a]:& - 10, c = 1.0 in CHC13) was obtained
by azidonitration of 3,4,6-tri-O-acetylgalactal and silylation of the free (anomeric) 1-OH group with tert-butyldimethylsilyl chloride (X-Cl)/imidazole (69%), deacetylation with sodium methoxide (88%), and benzylidenation
with benzaldehyde dimethyl acetal/p-toluenesulfonicacid
(78%). Under boron trifluoride-ether catalysis 1 and 2
react in dichloromethane at -20°C to afford the p(1-3)linked disaccharide 5[51(69%, m. p. = 238 "C (decomp.),
[a]& - 22, c = 1.0 in CHCl,), which upon treatment with
trifluoroacetic acid can be converted into the 4,6-unprotected disaccharide 6 (88%, m. p. = 203 ").
NPhth
ox
HO
'
[I] H. van Halbeek, L. Dorland, J. F. G. Vliegenhart, W. E. Hull, G. Lamblin,
M. Lhermitte, A. Boersma, P. Roussel, Eur. J . Biochem. 127 (1982)7, and
literature cited therein.
121 R. R. Schmidt, J. Michel, Angew. Chem. 92 (1980)763; 94 (1982)77;Angew. Chem. Int. Ed. Engl. 19 (1980)731;Angew. Chem. i n t . Ed. Engl. 21
(1982)77; G. Grundler, planned dissertation, Universitat Konstanz.-All
compounds were characterized by IR, 'H-NMR (250 MHz) and I3CNMR (62.97 MHz) spectroscopy, and by elemental analysis.
[3] Synthesis of the partially protected trisaccharide moiety
N3
CC13
l 2
G
AcO@~*~~
AcO
Ac
NPhth
Received: June 20, 1983 [ Z 425 IE]
German version: Angew. Chem. 95 (1983)805
CAS Registry numbers:
1, 87190-67-8;2, 87190-68-9;3, 81243-76-7;4, 87190-71-4;5, 87190-69-0;
6, 87190-70-3;7, 87206-73-3;8, 87190-73-6;
8-8 peracetate, 87248-21-3;a-8
peracetate, 87190-72-5;N-phthaloylJ,4,6-tri-o-acetylglucosamine,
87190-667;trichloracetonitrile, 545-06-2
Ph
AcO
dride to give the O-(2-amino-2-deoxylactosyl) trichloroacetimidate 4 (72%, [a]:&+43, c = O S in CHC13).
Under boron trifluoride-ether catalysis in dichloromethane at -20°C the disaccharides 4 and 6 led exclusively
to p(1-6)-~oupling~'~and, hence, to the tetrasaccharide 7
(71%, m.p.= 168-170°C, [a]::8+lo, c=0.5 in CHCI3).
The phthaloyl group was removed first from 7 with hydrazine. Acetylation using acetic anhydride/pyridine (64%)
and desilylation with tetrabutylammonium fluoride (74%)
yielded an intermediate which could be used to glycosylate
serine and threonine. I-0-Acetylation with acetic anhydride/pyridine, reduction of the azido group with
NiC12/NaBH4, and N-acetylation with acetic anhydride
afforded the completely acetylated tetrasaccharide as
a 1 :1 anomeric mixture 133%; 'H-NMR (250 MHz,
CDC13, TMS): 6 ~ 6 . 1 4(d, a-l-H, 51,2=3.7 Hz); 5.69 (d,
0-1-H, J1,2
= 8.9 Hz)]. The unprotected tetrasaccharide 8
([a]&=- 5 , c=0.2 in H 2 0 after 2 h) was obtained by
cleaving the 0-acetyl groups with potassium carbonate in
methanol (70%).
A ; Y o 6 : f Ni P h t h
N3
ox
G1cNAcS(1-6~GaINAca( 1-0-Bzi)
GlcNAcp( 1-3)
Ac
using the Koenigs-Knorr method: S. A. Abbas, J. J. Barlow, K. L. Matta,
Carbohydr. Res. 113 (1983)63.
[4]Synthesis after S. Akiya, T.Osawa, Chem. Pharm. Bull. 8 (1960) 583.
[5] The p-selectivity is attributable to the neighboring group activity of the Nphthaloyl group: H. Paulsen, Angew. Chem. 94 (1982) 184;Angew. Chem.
Inf. Ed. Engl. 21 (1982) 155, and literature cited therein.
ox
AcO
J.
GalP( 1 - 4) GlcNAc p( 1 - 6),
GalNAc 8
GlcNAcp(1-3)'
The lactosamine building block 3 was obtained from the
peracetylated lactal by azidonitration, silylation of the
anomeric 1-OH group with X-Cl/imidazole (63%), hydrogenation of the azido group with hydrogen, phthaloylation
of the amino group with phthalic anhydride, treatment of
the resultant compound with acetic anhydride/pyridine
(73%), and cleavage of the silyl group with tetrabutylammonium fluoride (88%, [a]::, +39, c = 1.0 in CHCl, after
2 h). 3 reacts with trichloroacetonitrile and sodium hyAngew. Chem Int. Ed. Engl. 22 (1983) No. 10
Reversal of the Regioselectivity in the
Zirconocene-Induced Coupling of a Ketone
with Isoprene**
By Gerhard Erker* and Ulrich Dorf
The reaction of (s-cis-isoprene)zirconocene 9 with organic carbonyl compounds often leads to regioselective
CC coupling at the diene terminus C1 adjacent to the methyl group13]. Recently, we showed that (s-trans-q4-butadiene)zirconocene reacts much faster with aldehydes and
ketones than the s-cis-isomer, with which it exists in equilibriumI6I. It was, therefore, expected that starting from
(isoprene)zirconocene the course of the reaction and,
hence, the regioselectivity of the CC coupling would also
[*I
[**I
Priv.-Doz. Dr.G.Erker, U. Dorf
Abteilung fur Chemie der Universitgt
Postfach 102148, D-4630Bochum 1 (Germany)
This work was supported by the Minister fur Wissenschaft und Forschung des Landes Nordrhein-Westfalen and by the Fonds der Chemischen Industrie.
0 Verlag Chemie GmbH, 6940 Weinheim. 1983
0570-0833/83/1010-0777 $02.50/0
177
change if it were allowed to react with ketones under conditions allowing participation of the s-trans-i~omer~~~.
We have now treated (isoprene)zirconocene 9 with 3,3dimethyl-2-butanone 13. The major product (=80%) of
the thermally induced reaction (benzene, 60°C, 2 h) is the
oxazirconacycloheptene lob, which can be hydrolyzed to
give alcohols l l b and 12b. Photolysis of 9 and 13 in toluene solution leads to competitive formation of both 10b
and its isomer 10a. The amount of 10a increases as the
temperature of the photolysis is lowered (Table 1). 10a is
also formed as the major product (= 75%) in the thermally
induced reaction of (s-trans-q4-isoprene)zirconocene7 and
13 at -70°C. Upon hydrolysis, only 12a is obtained. (See
Scheme 11.)
CAS Registry numbers:
7,75361-73-8; 9, 87185-18-0; lOa, 87185-19-1; lob, 87185-20-4; Ilb, 8718522-6; 12a, 87185-21-5: 12b, 87185-23-7; 13, 75-97-8; isoprene, 78-79-5; zirconocene, 12116-83-5
121 b) U. Dorf, K. Engel, G. Erker, Organometallics 2 (1983) 462.
[3] H. Yasuda, Y.Kajihara, K. Mashima, K. Nagasuna, A. Nakamura, Chem.
Lett. 1981, 671; M. Akita, H. Yasuda, A. Nakamura, ibid. 1983, 217.
151 G. Erker, J. Wicher, K. Engel, C. Kriiger, Chem. Ber. 115 (1982) 3300.
161 G. Erker, K. Engel, J. L. Atwood, W. E. Hunter, Angew. Chem. 95 (1983)
506; Angew. Chem. Int. Ed. Engl. 22 (1983) 494; Angew. Chem. Suppl.
1983, 615.
171 G. Erker, K. Engel, U. Dorf, J. L. Atwood, W. E. Hunter, Angew. Chem.
94 (1982) 915; Angew. Chem. Int. Ed. Engl. 21 (1982) 913; Angew. Chem.
Suppl. 1982, 1974.
1
Diels-Alder Reactions of Dienes with Alkynes
Catalyzed by Diazadieneiron
By Heindirk tom Dieck* and Reiner Diercks
Dedicated to Professor Karl Winnacker on the occasion of
his 80th birthday
Diels-Alder reactions between simple dienes and alkynes proceed thermally only under somewhat drastic conditions. We have now found that iron compounds modified by 1,4-diaza-1,3-dienes (dad) 4 as directive ligands catalyze the [4 2lcycloaddition of simple dienes with nonterminal alkynes at room temperature (R in dad, see Table 1).
The same substrates yield 2 :1 adducts or 2 :2- and 1 :2-cooligomers with ligand-nickel catalystsF3].With bis(cyc1ooctatetraene)iron as catalyst, 1 : 1-adducts have been described14].
+
L
1
[Ila
CH3C[CH3)=CHCHzCR'R20H)
12a
CH~=CKH,)CH~CH~CR'R%H
I
I
13
CH3CH=C(CH3)CH2CR'RZOH l l b
+
CH~=CHCH(CH~)CH~CR'R%H 12b
R
I
R
I
R'= - C H ~ Rz= - C ( C y h
Scheme
Activator
I1
4
Table 1. Reaction of (isoprene)zirconocene 9 with the ketone 13: product ratio 10b/10a as a function of the reaction conditions.
~
A
10b
10n
+60T
+37"C
0°C
hv
-40°C
-78°C
86
14
81
19
56
44
37
63
22
78
The regioselectivity achieved [product ratio ( l l b + 12b)/
12a] was determined by gas chromatography (Table 1). In
the thermally induced reaction of 9 and 13, CC coupling
at C1 of the diene is favored by > 80/ < 20 relative to coupling at C4. When the irradiation is carried out at lower
temperatures, the pathway via the very reactive intermediate (q*-isoprene)zirconocene complexes 8 becomes increasingly i m p ~ r t a n t [ Here,
~ ~ ~ the
~~~
ketone
~ . couples preferentially with the less substituted olefin moiety. Irradiation of the reaction mixture at sufficiently low temperatures or reaction of the pure (s-trans-q4-isoprene)zirconocene isomer 7 eventually results in reversal of the observed
regioselectivity : with 22/78 the product 10a arising from
coupling at C4 of the isoprene unit, i. e. away from the methyl group, is formed predominantly.
Received: June 1, 1983 [Z 406 IE]
German version: Angew. Chem. 95 (1983) 800
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1983, 1120-1129
778
hene
Alkyne
0 Verlag Chemie GmbH, 6940 Weinheim. 1983
=
R
R
dad
5
"(dad)Feo"
+
1-3
The readily accessible complexes (dad)FeCl, 5 are activated in the presence of diene and alkyne using reducing
agents such as triethylaluminum, alkylmagnesium halides, or
magnesium-isoprene.2THF. Bis(diazadiene)iron, (dad)zFe
6c, also gives rise to an active catalyst with MEt3 at
90 "C, just as do the multicomponent systems
Fe(acac),/2dad/4AlEt3 7a or Fe(acac),/2dad/6EtMgBr
8a.
Table 1 indicates that the results depend on the substituents R on the ligand 4. Under the conditions investigated
to date, only N,W-dialkyldiazadienes are active; in contrast, N, N'-diaryldiazadienes, which are highly active in
diene cyclodimerizations, are not[". Since in the reaction of
rrans-1,3-pentadiene with 3-hexyne to afford 2 a center of
chirality is formed, complexes with chiral dad (4g-i)
were also used. Although 2 is also formed in good yield
with 5g- i, optical induction-in contrast to diene cyclodimerization using the same precatalyst"]-could not be detected.
[*] Prof. Dr. H. tom Dieck, R. Diercks
[**I
Institut fur Anorganische und Angewandte Chemie der Universitat
Martin-Luther-King-Platz 6, D-2000 Hamburg 13 (Germany)
This work was supported by the Deutsche Forschungsgemeinscbaft. R .
D. thanks the Fonds der Chemischen Industrie for a grant. Prof. A .
Krebs and Hoechst AG are thanked for samples of cyclooctyne and
trans- 1,3-pentadiene, respectively.
0570-0833/83/1010-0778 $02.50/0
Angew. Chem. hi.Ed. Engl. 22 (1983) No. I 0
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induced, reversal, zirconocene, couplings, ketone, refioselectivity, isoprene
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