Titanocene(III) Chloride Mediated Radical-Induced Addition to Baylis−Hillman Adducts: Synthesis of (E)- and (Z)-Trisubstituted Alkenes and α-Methylene/Arylidene δ-Lactones
摘要:
Baylis-Hillman adduct underwent smooth radical-induced condensation with activated bromo compounds and epoxides using titanocene(III) chloride (CP2TiCl) as the radical generator. The reactions of activated bromo compounds with 3-acetoxy-2-methylene alkanoates provided (E)-alkenes exclusively, whereas similar reactions with 3-acetoxy-2-methylenealkanenitriles led to (Z)-alkenes as the major product. The reactions of epoxides with Baylis-Hillman adduct furnished alpha-methylene/arylidene-delta-lactones in good yield via addition followed by in situ lactonization.
Morita-Baylis-Hillman adducts undergo smooth allylic nucleophilic substitution (SN2′) with allyltrimethylsilane in the presence of BF 3 ·OEt 2 under mild reaction conditions to afford 1,5-diene derivatives in good yields with high selectivity.
Acetates of Baylis-Hillman adducts derived from ethyl acrylate, methyl vinyl ketone, and acrylonitrile were coupled with allyltributylstannane using Pd(PPh3)4 or Pd(dba)2 as the catalyst at room temperature to afford the corresponding trisubstituted alka-1,5-dienes in good to high yields.
Titanocene(III) Chloride Mediated Radical-Induced Addition to Baylis−Hillman Adducts: Synthesis of (<i>E</i>)- and (<i>Z</i>)-Trisubstituted Alkenes and α-Methylene/Arylidene δ-Lactones
作者:Samir K. Mandal、Moumita Paira、Subhas C. Roy
DOI:10.1021/jo800049p
日期:2008.5.1
Baylis-Hillman adduct underwent smooth radical-induced condensation with activated bromo compounds and epoxides using titanocene(III) chloride (CP2TiCl) as the radical generator. The reactions of activated bromo compounds with 3-acetoxy-2-methylene alkanoates provided (E)-alkenes exclusively, whereas similar reactions with 3-acetoxy-2-methylenealkanenitriles led to (Z)-alkenes as the major product. The reactions of epoxides with Baylis-Hillman adduct furnished alpha-methylene/arylidene-delta-lactones in good yield via addition followed by in situ lactonization.