The synthesis of β‐amino acid derivatives (III) and (V), versatile precursors for preparation of polyamine alkaloids, is achieved by asymmetric conjugate addition of cyclic hydrazines (II) and (IV).
Asymmetric cycloaddition of 1-phenoxycarbonyl- (1) or 1-methoxycarbonyl-1,2-dihydropyridine (2) with N-acryloyl-(1S)-2,10-camphorsultam (3) produced chiral isoquinuclidine 4a or 5a in good yields with excellent diastereoselectivity in the presence of a Lewis acid such as titanium tetrachloride, zirconium tetrachloride, or hafnium tetrachloride. The absolute stereochemistry assignment of endo-cycloaddition products 4a and 5a has been established to be 1S, 4R, and 7S.
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