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Preparation and stereochemistry of methyl 3‐(and 4)‐ p ‐chlorothiophenoxy‐1‐methylpiperidine‐4‐(and 3)‐carboxylates, and cyclization to benzothiopyranopyridinones
Author(s) -
Butt Graeme L.,
Deady Leslie W.,
Mackay Maureen F.
Publication year - 1988
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570250154
Subject(s) - chemistry , chlorobenzene , sulfuric acid , stereochemistry , product (mathematics) , medicinal chemistry , organic chemistry , catalysis , geometry , mathematics
The title piperidines were prepared by (a) methanolysis of the corresponding nitriles and (b) addition of p ‐chlorothiophenol to the appropriate tetrahydropyridines. Three esters were obtained with stereochemistry assigned by nmr analysis: 2 [3(a) SAr, 4(e) CO 2 Me], 5 [4(e) SAr, 3(e) CO 2 Me], 6 [4(a) SAr, 3(e) CO 2 Me]. Compounds 2 and 6 cyclized in 70% sulfuric acid. The product structures were established by X‐ray crystallography and, surprisingly, both had trans‐fused rings. Compound 5 , however, did not cyclize but gave 4‐(methylthio)chlorobenzene as the sole isolated product.