Cyclization aminocyclopropanes

PLP-dependent enzymes catalyze the following types of reactions (1) loss of the ce-hydrogen as a proton, resulting in racemization (example alanine racemase), cyclization (example aminocyclopropane carboxylate synthase), or j8-elimation/replacement (example serine dehydratase) (2) loss of the a-carboxylate as carbon dioxide (example glutamate decarboxylase) (3) removal/replacement of a group by aldol cleavage (example threonine aldolase and (4) action via ketimine intermediates (example selenocysteine lyase). 

A similar 3-(2-bromoethyl) derivative has been utilized to synthesize 1-aminocyclopropane-1 -carboxylic acid by an intramolecular base-catalyzed cyclization. This was possible when position 6 was blocked by the presence of two substituents. Some unexpected stereochemical results also came up in this study (85MI2). The starting material was the piperazine-2,5-dione derived from (/ )-(+ )-2-methyl-3-phenylalanine and glycine. The bislactim ether derived from this, on treatment with butyl lithium in THF at -78°C, gave the lithio derivative. Alkylation of this with 2-haloethyl... 

Various bicyclic compounds with an aminocyclopropane structural unit (azaquadricyclanes , azabarbaralanes or azaprismanes " ) were obtained by photochemical cyclization of suitable precursors with CC double bonds (e.g. 363 364)... 

J.K. Cha et al. developed a stereocontrolled synthesis of bicyclo[5.3.0]decan-3-ones from readily available acyclic substrates. Acyclic olefin-tethered amides were first subjected to the intramolecular Kulinkovich reaction to prepare bicyclic aminocyclopropanes. This was followed by a tandem ring-expansion-cyclization sequence triggered by aerobic oxidation. The reactive intermediates in this tandem process were aminium radicals (radical cations). The p-anisidine group was chosen to lower the amine oxidation potential. This substituent was crucial for the generation of the aminium radical (if Ar = phenyl, the ring aerobic oxidation is not feasible). 

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