The condensation of 2,2-dimethyl-7-nitro-2H-1-benzopyran-6-amine (I) with 4-methoxyphenylacetyl chloride (II) by means of triethylmaine in chloroform gives the corresponding amide (III), which is regioselectively epoxidized with ClONa and a chiral manganese catalyst yielding the epoxide (IV). Finally, this compound is treated with cyclopropylamine in refluxing ethanol.
The acylation of 6-amino-2,2-dimethyl-7-nitro-2H-1-benzopyran (I) with p-methoxyphenylacetyl chloride (II) furnished amide (III). Subsequent bromination of the pyran ring of (III) employing N-bromosuccinimide in H2O-DMSO formed the trans bromohydrin (IV), which was further cyclized to epoxide (V) upon treatment with NaOH. Finally, oxirane ring opening in (IV) with cyclopropylamine (VI) in boiling EtOH yielded the title trans amino alcohol.