The synthesis of (−)-cis- and (−)-trans-crobarbatic acid
摘要:
The synthesis of both cis- and trans-crobarbatic acid is reported. The five-step sequence proceeds in high yield and with control of both relative and absolute stereochemistry. The key step in the synthesis is the Birch reductive alkylation of a chiral furoic acid which sets the absolute stereochemistry of the products. The stereochemistry of the compounds described was proven unambiguously by X-ray crystallography on one synthetic intermediate and on trans-crobarbatic acid. (C) 1999 Elsevier Science Ltd, All rights reserved.
Oxidative rearrangement of 2-alkoxy-3,4-dihydro-2H-pyrans: stereocontrolled synthesis of 4,5-cis-disubstituted tetrahydrofuranones including whisky and cognac lactones and crobarbatic acid
Oxidation of 2-alkoxy-3,4-dihydro-2H-pyrans 3 with dimethyldioxirane or MTO/urea–H2O2 followed by Jones oxidation leads to rearrangement and stereocontrolled formation of 4,5-cis-disubstituted tetrahydrofuranones. The method is applied to the synthesis of the whisky lactone 9, cognac lactone 10 and crobarbatic acid 17.
用二甲基二环氧乙烷或MTO /脲-H 2 O 2氧化2-烷氧基-3,4-二氢-2 H-吡喃3,然后进行琼斯氧化,导致4,5-顺式-二取代的四氢呋喃酮的重排和立体形成。该方法适用于威士忌内酯9,白兰地内酯10和巴巴果酸17的合成。
Diastereoselective reactions of pyruvates with but-2-enyl organometallic compounds. Stereocontrol at the tertiary carbon centre
The reaction of pyruvates (3) with but-2-enyl-9-borabicyclo[3.3.1]nonane(2a) or its α-silyl and α-stannyl substituted derivatives (10) produced the threo-isomer [(4) or (11), respectively] stereoselectively; the latter reaction was applied to the synthesis of cis-crobarbatic acid(14).