336193-86-3Relevant academic research and scientific papers
Synthesis of chiral pyrrolo[1,2-c]thiazoles via intramolecular dipolar cycloaddition of muenchnones: An interesting rearrangement to pyrrolo[1,2-c]thiazines
Pinho e Melo, Teresa M. V. D.,Soares, Maria I. L.,Rocha Gonsalves, Antonio M. d'A.,Paixao, Jose A.,Beja, Ana M.,Ramos Silva, Manuela,Alte da Veiga, Luiz,Costa Pessoa, Joao
, p. 4045 - 4054 (2007/10/03)
Intramolecular dipolar cycloaddition of bicyclic muenchnones, 5H,7H-thiazolo[3,4-c]oxazol-4-ium-1-olates, derived from cyclodehydration of 2-substituted-N-acylthiazolidine-4-carboxylic acids are reported. A range of new pyrrolo [1,2-c] thiazole derivatives (7, 14, 15, 20, 23, and 26) were obtained as single enantiomers from 2-phenylthiazolidines, 2-benzoylthiazolidines, and 2-methylthiazolidine-4-carboxylates. Pyrrolo[1,2-c][1,4]thiazine derivative 27 was also obtained from pyrrolo[1,2-c]thiazole derivative 26. The structures of methyl (2R,4R)-2-(p-methoxybenzoyl)thiazolidine-4-carboxylate (17a), methyl (2R,4R)-2-(p-methoxybenzoyl)-N-(prop-2- ynyloxyacetyl)thiazolidine-4-carboxylate (18), and 3-oxo-4-phenyl-3,4,6,8-tetrahydro-1H-furo [3′,4′:2,3]pyrrolo[1,2-c][1,4]thiazine (27) were determined by X-ray crystallography. Chirooptical studies of the pyrrolo[1,2-c]thiazoles were done by confirming the absolute configuration at the chiral center C-3.
'Hidden' Axial Chirality as a Stereodirecting Element in Reactions Involving Enol(ate) Intermediates. Part 1. Cyclisation Reactions of Methyl (4R)-3-(2-Diazo-3-oxobutanoyl)thiazolidine-4-carboxylate and Related Compounds
Beagley, Brian,Betts, Michael J.,Pritchard, Robin G.,Schofield, Anthony,Stoodley, Richard J.,Vohra, Shaheen
, p. 1761 - 1770 (2007/10/02)
Methyl (4R)-3-(2-diazo-3-oxobutanoyl)thiazolidine-4-carboxylate 1b underwent cyclisation, under a variety of basic conditions, to give methyl (6S)-2-oxo-8-thia-1,4,5-triazabicyclonon-3-ene-6-carboxylate 2a in an enantiopure state.The absolute configuration of compound 2a was deduced by X-ray crystallography.Similar stereoselective cyclisations, proceeding with retention of configuration, were observed with methyl (4R)-3-thiazolidine-4-carboxylate 1g (to give compound 5a), methyl (4R)-3-(2-diazo-3-oxobutanoyl)-2,2-dimethylthiazolidine-4-carboxylate 20a (to give compound 21a) and methyl (2R,4R)-3-(2-diazo-3-oxobutanoyl)-2-methylthiazolidine-4-carboxylate 22a (to give compound 24).An X-ray crystallographic analysis of compound 22a revealed that the amide and diazo ketone units, although individually near planar, were twisted from each other by 35 deg; it was notable that the amide linkage adopted the (Z)-geometry required for the cyclisation reaction whereas the diazo moiety was incorrectly aligned.It is suggested that the cyclisation reactions proceed by way of planar enol(ate) intermediates, e.g. 6a, which possess axial chirality.
