Thionation of ω-hydroxy amides with Lawesson's reagent: Synthesis of thioenamides and sulfur-containing heterocycles
摘要:
The thionation of omega-hydroxy amides with Lawesson's reagent [LR: 2,4-bis(p-methoxyphenyl)- 1,3,2,4-dithiaphosphetane-2,4-disulfide] is described. The treatment of 3-hydroxy amides 1 with LR exclusively gave thioenamides 2 in fair yields. The treatment of 4-hydroxy amides 5 with LR yielded sulfur-containing heterocycles such as tetrahydrothiophene-2-imines 6 and tetrahydrothiophene-2-thione 7a through cyclization of intermediates, 4-mercapto amides 8. The 5-hydroxy amides 13 also reacted with LR to afford tetrahydrothiopyrane-2-thione 14 as the the sole product. (C) 1999 Elsevier Science Ltd. All rights reserved.
A Polar Effects Controlled Enantioselective 1,2-Chlorine Atom Migration via a Chlorine-Bridged Radical Intermediate
作者:Eng Wui Tan、Bun Chan、Allan G. Blackman
DOI:10.1021/ja011129r
日期:2002.3.1
An enantioselective 1,2-chlorine atom migration was observed in the tributyltin hydride reduction of various dihalogenated dihydrocinnamic acid derivatives. It is proposed that the reduction involves the formation of a chlorine-bridged radical intermediate, followed by hydrogen atom transfer to either the beta- or the alpha-carbon. The product distribution is affected by electron-withdrawing groups
A novel process for the preparation of tolterodine, i.e. (R)-N,N-diisopropyl-3-(2-hydroxy-5-methylphenyl)-3-phenylpropanamine, in the racemic form, as well as intermediates useful for its preparation.