Reversing one or more of the amide groups (ie CHRCONH to CHRNHCO) of a linear peptide gives a so-called" partially modified retro isomer" and represents an important strategy in peptide analogue research.'" Y2 The modified sequence requires both a malonic unit and a (much less easily available) a, a-diamino moiety. Such a, a-diamino units have been synthesized by C urti~ s-'~~~~ or H~ ffmann-type~*~ p~ rearrangements of protected ...
