Atropisomeric N-acyl-N-(cyclopentenylphenyl)glycines in the synthesis of oxazolo[3,4-a]benzoxazocinones

An Unexpected Dihalogenation/Dehydrogenation Product Derived­ via Iodolactonization of an N-Tosyl-N-[6-(2-cyclopenten-1-yl)-2-methylphenyl]glycine

“…To a solution of compound 3 19 (2.41 g, 9.8 mmol) in pyridine (8 mL) was added tosyl chloride (3.9 g, 20 mmol). (At room temperature, the tosylation reaction is slow, but after 24 h a small amount of precipitate emerges.)…”

“…For this purpose, reacting toluenesulfonylamide 2 18 (the toluenesulfonylamide sodium salt) with methyl bromoacetate gave compound 1. Ester 1 could also be synthesized by tosylation of compound 3, 19 itself obtained from cyclopentenyltoluidine 4. Compound 1 was saponified with lithium hydroxide solution in aqueous THF to obtain acid 5 (Scheme 1).…”