Stereoselective Addition of the Titanium Enolate of <i>N</i>-Acetyl (4<i>S</i>)-Isopropyl-1,3-thiazolidine-2-thione to Five-Membered <i>N</i>-Acyl Iminium Ions
作者:Efraín Barragán、Horacio F. Olivo、Moisés Romero-Ortega、Seth Sarduy
DOI:10.1021/jo050188a
日期:2005.5.1
Addition of the chlorotitanium enolate of N-acetyl 4-isopropyl-1,3-thiazolidine-2-thione to five-membered, N-Substituted N-acyl iminium ions furnished the corresponding Mannich-type addition products with good diastereoselectivity and in good yields. The synthetic utility of the addition product 8 was demonstrated in a chemospecific anti-aldol reaction with cinnamaldehyde. By using this strategy, we
Convenient route to both enantiomers of chiral 5-hydroxypyrrolidin-2-one and 5-hydroxy-1,5-dihydropyrrol-2-one: reverse enantioselectivity in lipase-catalyzed kinetic resolution
作者:Kunihiko Takabe、Masahisa Suzuki、Toshiki Nishi、Masaomi Hiyoshi、Yasuaki Takamori、Hidemi Yoda、Nobuyuki Mase
DOI:10.1016/s0040-4039(00)01745-7
日期:2000.12
High enantioselectivity was achieved in the lipase-catalyzedkineticresolution of 5-hydroxypyrrolidin-2-one and 5-hydroxy-1,5-dihydropyrrol-2-one derivatives. Lipase PS and Novozym 435 were the successful catalysts (E=>1000). The acetylation of the N-protected 5-hydroxy-1,5-dihydropyrrol-2-one derivative gave the (R)-acetate with high enantioselectivity, while, without N-protection, the (S)-acetate