Exploratory Studies on the Synthesis of Unsymmetrically Substituted Diacetylenes Bearing Trialkoxysilyl Groups and Development of a Method for the Preparation of 1-Lithio-4-(2,8,9-trioxa-5-aza-1-silab
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- 作者：Luc Brunel ; Gé ; rald Chaplais ; Sylvain G. Dutremez ; Christian Gué ; rin ; Bernard J. L. Henner ; and Vé ; ronique Tomberli
- 刊名：Organometallics
- 出版年：2000
- 出版时间：June 26, 2000
- 年：2000
- 卷：19
- 期：13
- 页码：2516 - 2525
- 全文大小：340K
- 年卷期：v.19,no.13(June 26, 2000)
- ISSN：1520-6041
文摘
(Z)-CH3OCH=CHCG SRC="/images/entities/tbd1.gif">CSi(OCH3)3 (2), ((Z)-CH3OCH=CHC
ges/entities/tbd1.gif">C)2Si(OCH3)2 (5), and (Z)-CH3OCH=CHCges/entities/tbd1.gif">CSi(OCH(CH3)2)3 (16) have been synthesized from (Z)-CH3OCH=CHCges/entities/tbd1.gif">CH (1).Enynes 2 and 16 were subjected to a deprotonation-elimination-deprotonation sequencewith 2 equiv of lithium diisopropylamide (LDA) in THF and the expected intermediates(RO)3SiCges/entities/tbd1.gif">CCges/entities/tbd1.gif">CLi (R = CH3, CH(CH3)2) allowed to react with R'3SiCl (R' = CH3, C6H5) toproduce the unsymmetrical butadiynes (RO)3SiCges/entities/tbd1.gif">CCges/entities/tbd1.gif">CSiR'3. Symmetrical butadiynes ofthe type R'3SiCges/entities/tbd1.gif">CCges/entities/tbd1.gif">CSiR'3 were obtained instead of the expected unsymmetrical ones dueto cleavage of the Csp-Si(OR)3 bond by CH3OLi formed in situ. Cleavage of the latter bondcan be avoided by using a silatrane moiety in place of the trialkoxysilyl group. Thus, (CH3)3SiCges/entities/tbd1.gif">CCges/entities/tbd1.gif">CSi(OCH2CH2)3N (26a) and (C6H5)3SiCges/entities/tbd1.gif">CCges/entities/tbd1.gif">CSi(OCH2CH2)3N (26b) were obtained in 61% and 45% yield, respectively, upon subjecting (Z)-CH3OCH=CHCges/entities/tbd1.gif">CSi(OCH2CH2)3N (20) to a deprotonation-elimination-metalation sequence with 2 equiv of LDAfollowed by quenching of the intermediate lithium compound LiCges/entities/tbd1.gif">CCges/entities/tbd1.gif">CSi(OCH2CH2)3N(25) with (CH3)3SiCl and (C6H5)3SiCl. The deprotonation-elimination-metalation sequenceapplied to 20 is best carried out in pyridine, and the role of pyridine in this reaction isdiscussed.