190260-52-7Relevant articles and documents
Synthesis and oxidation of chiral 2-thiazolines (4,5-dihydro-1,3-thiazoles)
Aitken, R. Alan,Armstrong, David P.,Galt, Ronald H. B.,Mesher, Shaun T. E.
, p. 935 - 943 (2007/10/03)
Eight new chiral 2-thiazolines (4,5-dihydro-1,3-thiazoles) 2 have been prepared by treatment of the 2-methyloxazolines 1, the benzoylamino alcohols 4 or the trimethylacetylamino alcohols 5 with P2S5. With a 2-methyl substituent, reaction with Oxone results in ring-opening to give the acetylamino disulfides 9 and with MCPBA there is also ring-opening with incorporation of a m-chlorobenzoyl group to give 12. Treatment of the 2-phenyl compounds with a variety of oxidants gives the benzoylamino sulfonic acids 10 and the disulfides 9 together with the thiazoles 11 in varying proportions. The sulfonic acids and thiazoles are obtained in pure form by reaction with 3 equiv. of peracetic acid and with sulfur, respectively. Although reaction of 2d-f with KMnO4 under phase-transfer conditions gives the thiazoles 11, addition of 1 equiv. of benzoic acid results in a complete change in selectivity to afford the thiazoline 1,1-dioxides 3d-f in excellent yield. These compounds prove to be exceptionally moisture-sensitive and readily hydrolyse to give the benzoylamino sulfinic acids 8 whose further oxidation and disproportionation probably explains the formation of the sulfonic acids and disulfides with the other oxidants. The high reactivity of the sulfones 3 towards nucleophilic ring-opening precludes their deprotonation and alkylation. Upon flash vacuum pyrolysis at 600°C, they fragment to give SO2, benzonitrile and the alkenes 16 in high yield. Fully assigned 13C NMR spectra are presented for the 18 heterocyclic compounds prepared and for 17 acyclic derivatives.
