Treatment of silyl enolates with methyllithium followed by an addition of galliumtrichloride afforded the corresponding gallium enolates. The reaction of the resulting gallium enolates with α-halo carbonyl compounds in the presence of triethylborane as a radical initiator provided 1,4-dicarbonyl compounds in good yields.
CRYSTAL OF SPIROKETAL DERIVATIVES AND PROCESS FOR PREPARATION OF SPIROKETAL DERIVATIVES
申请人:Chugai Seiyaku Kabushiki Kaisha
公开号:US20140024817A1
公开(公告)日:2014-01-23
The present invention provides a process for preparing a spiroketal derivative, via an intermediate represented by Formula (VI):
wherein variable groups and numbers are as defined in the specification, which can be produced from dihalobenzene derivatives in one pot reaction.
Acyl radicals are invaluable intermediates in organic synthesis, however their generation remains challenging. Herein, we present an unprecedented light‐driven, cobalt‐catalysed method for the generation of acyl radicals from readily available 2‐S‐pyridyl thioesters. The synthetic potential of this methodology was demonstrated in the Giese‐type acylation of activated olefins in the presence of heptamethyl
yeast carefully studied. Both 4-oxopentanenitrile and 5-oxohexanenitrile are reduced in moderate yields to the corresponding (S) alcohols of high ee while other substrates gave products of varying optical purities. These alcohols are useful intermediates for the preparation of chiral lactones, including the synthetically important (S)(−)-4-methylbutyrolactone and (S)-(−)-5-hexanolide.
摘要 已经合成了许多 γ 和 δ 酮腈,并仔细研究了它们用面包酵母的还原。4-氧代戊腈和 5-氧代己腈均以中等产率还原为相应的高 ee (S) 醇,而其他底物产生不同光学纯度的产物。这些醇是制备手性内酯的有用中间体,包括合成重要的 (S)(-)-4-甲基丁内酯和 (S)-(-)-5-己内酯。