Synthesis of Medium Ring Ethers. 5. The Synthesis of (+)-Laurencin
作者:Jonathan W. Burton、J. Stephen Clark、Sam Derrer、Thomas C. Stork、Justin G. Bendall、Andrew B. Holmes
DOI:10.1021/ja9709132
日期:1997.8.1
enantioselective synthesis of (+)-laurencin 1 has been achieved in 27 steps from (R)-malic acid 20. The key steps involved methylenation of the lactone 49 followed by intramolecular hydrosilation of the enol ether 14 (Scheme 11) and one carbon homologation of the diol 13 to give the key ethyl substituted cyclic ether 59 (Scheme 13). The lactone 49 was obtained by two efficient routes, namely a Claisen ring expansion
Enyne Chlorides: Substrates for Copper-Catalyzed Asymmetric Allylic Alkylation
作者:Hailing Li、Alexandre Alexakis
DOI:10.1002/anie.201107129
日期:2012.1.23
A select few: Several prochiral enynechlorides were employed as substrates in the title reaction using Grignard reagents as the alkylation reagents (see scheme; CuTC=copper(I) thiophenecarboxylate). Excellent 1,3 substitution regioselectivities and good to excellent enantioselectivities were obtained. The substrate scope is additionally extended to diene chlorides.
Abstract 1,1-Bis(trimethylsilyl)-2-propyne, prepared from propargyltrimethylsilane, was reacted, in the presence of a Lewis acid, with electrophiles (aldehydes, acetals) to afford (E)-silylated conjugated enynes.