Stereospecific reactions of cis- and trans-3-Aminochroman-4-ols

Abstract

Stereospecific reactions of epimeric 3-amino-6-methylchroman-4-ols (1 and 2; R = Me) have provided chemical evidence for their configuration and have led us to reverse the configurations that we had assigned previously to the 6-bromo analogues on the basis of N.M.R. data.     The 2-chloro-N-(4-hydroxy-6-methylchroman-3-yl)acetamides (3) and (4) were treated with potassium hydroxide in ethanol in an attempt to effect ring closure. The cis-chloroacetamide (4) gave a cyclic amide (5) while the trans-chloroacetamide (3) reacted with solvent to form the trans-3-ethoxyacetamidochroman-4-ol (6).     The configurations of the amino alcohols were confirmed by a study of their reactions with nitrous acid where deamination of the cis-amino alcohol gave the chroman-4-one (9) while the trans-amino alcohol gave a trans-diol (10) by an epoxide intermediate.