Cyclopropyl building blocks for organic synthesis, 58 - A new short accessto amino acids incorporating an aminocyclopropyl moiety from N,N-dibenzylcarboxamides

Our recently reported titanium-mediated transformation of N,N-dialkylcarbox amides to cyclopropylamines has been applied to N,N-dibenzyl-2-benzyloxyace tamide using a variety of alkylmagnesium bromides to yield 1-(benzyloxymeth yl)-1-(dibenzylamino)cyclopropane (15a, 48%) and 2-substituted analogs 15b- f (33-48%). These have been transformed in just a few steps into N-Boc-prot ected methyl esters of 1-ami-nocyclopropanecarboxylic acid (1, 29% overall) , coronamic acid (2, 35%) and norcoronamic acid (21%), 2,3-methanoglutamic acid (21g, 19%) and 2,3-methanoornithine (21I, 12%). Similarly, the corresp onding derivatives of 3,4-methano-gamma-aminobutyric acid (26, 23%) and 4-s pirocyclopropane-gamma-butyrolactam (32, 44%) have been synthesized.