Stereoselective addition of the titanium enolate of N-acetyl (4S)-isopropyl-1,3-thiazolidine-2-thione to five-membered N-acyl iminium ions.
[reaction: see text] 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 constructed three contiguous chiral centers with high stereocontrol employing the same chiral auxiliary. X-Ray crystallographic analysis of addition product 2 and aldol product 14 revealed their absolute stereochemistry.
Barragán
Efraín
E
Division of Medicinal and Natural Products Chemistry, College of Pharmacy, The University of Iowa, Iowa City, Iowa 52242, USA.
Olivo
Horacio F
HF
Romero-Ortega
Moisés
M
Sarduy
Seth
S
D007097:Imines / Q000737:chemistry*; D013237:Stereoisomerism; D013844:Thiazoles / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
D007097:Imines; D013844:Thiazoles; D014025:Titanium