Novel α-substituted β-amino diesters from acylnitroso-derived hetero-Diels–Alder cycloadducts

α-Methyl β-amino diesters were synthesized in a simple three-step procedure starting from acylnitroso-derived Diels–Alder adducts of cyclopentadiene. Treatment of the cycloadducts with copper catalyst-modified methylmagnesium bromide gave anti-1,2-cyclopentenyl hydroxamic acids. Reduction of the hydroxamate NO bond with titanium(III) chloride followed by ozonolytic cleavage of the cyclopentenyl olefin provided the desired α-methyl β-amino diesters.