A highly diastereoselective synthesis of the taxane potential precursor 16 is achieved. An unexpected diastereoselectivity was observed upon condensation of the α-trimethylsilyloxyaldehydes 9a or 9b with the cyclohexenyllithium 10. The single diol isomers 13A and 14A exhibiting the required 1β,2α relative configuration are obtained in good yields.
The present invention provides three basic routes for the total synthesis of taxol having the structure: ##STR1## The present invention also provides the intermediates produced in the above processes, processes for synthesizing these intermediates as well as analogues of taxol and nortaxol.
Two different reactions were experimented for the construction of the eight-membered B-ring of taxane skeleton through the formation of the C9C10 bond. A SmI2 promoted radical reaction on seco-alkynyl aldehydes 11cis or 11trans failed. A Nozaki/Kishi reaction carried out on the seco-iodovinyl aldehyde 12trans led, through an unprecedented intramolecular SN2′ reaction, to the “abnormally” cyclised product
A convergent approach to substituted phenanthrenes via quinol ketals
作者:Tina M. Marks、Gary W. Morrow
DOI:10.1016/s0040-4039(00)74186-4
日期:1992.4
Reaction of 2'-lithiostyrenes with p-benzoquinone monoketals gives p-quinol ketals which undergo Lewis acid-catalyzed cyclization and aromatization, affording 2-methoxyphenanthrenes.
Generation and intramolecular cyclization of (2-ethenylphenyl)bisketenes. Synthesis of benzofuranones
作者:Matthew J Heileman、Harold W Moore
DOI:10.1016/s0040-4039(98)00638-8
日期:1998.5
Several new differentially substituted cyclobutenediones 4a-e have been prepared. Their thermal rearrangement to substituted naphthofuranones 5a-d is reported. This rearrangement involves an unprecedented intramolecular cyclization of a reactive bisketene 6, and forms the naphthofuranone system in good yield. (C) 1998 Elsevier Science Ltd. All rights reserved.