Cycloaddition of delta2-thiazolines and acyl ketenes under acidic conditions results in bicyclic 1,3-oxazinones and not 6-acylpenams as earlier reported.
[reaction: see text] Optically active Delta(2)-thiazolines 4 were previously reported to react with acyl Meldrum's acid derivatives 5 under acidic conditions (HCl (g) in benzene) to stereoselectively give 6-acylpenams 1. Recently we have discovered that the structure elucidation of these compounds was incorrect. Thus, we report new data showing that instead of acyl beta-lactams, the optically active isomers 3R,9R-1,3-oxazinones 3a-g are obtained stereoselectively in 38-93% yields.
Pemberton
Nils
N
Organic Chemistry and Inorganic Chemistry, Umeå University, S-901 87 Umeå, Sweden.
Emtenäs
Hans
H
Boström
Dan
D
Domaille
Peter J
PJ
Greenberg
William A
WA
Levin
Michael D
MD
Zhu
Zuolin
Z
Almqvist
Fredrik
F
D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000138:chemical synthesis*; D002384:Catalysis; D003500:Cyclization; D005030:Ethylenes / Q000737:chemistry; D007659:Ketones / Q000737:chemistry; D010078:Oxazines / Q000138:chemical synthesis*; D013237:Stereoisomerism; D013844:Thiazoles / Q000737:chemistry*; D047090:beta-Lactams / Q000138:chemical synthesis* / Q000737:chemistry
D019086:Bridged Bicyclo Compounds, Heterocyclic; D005030:Ethylenes; D007659:Ketones; D010078:Oxazines; D013844:Thiazoles; D047090:beta-Lactams; C008223:ketene