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Regio and stereochemistry of the title reaction appear to be strongly influenced by the nature of both organometallic and allylic reagents. The results are discussed in view of the intervention of ion-pair intermediates.

The isomeric alkenes 1 – 4 have been obtained by syn , γ substitution of the appropriate allylic carbamates with Li2Cu3Me5. The behaviour of carbamates is deeply affected by the nature of the copper reagent.

cis -3-Guanidino-L-proline and capreomycidine have been obtained by catalytic hydrogenation of viomycidine. The configuration of the 3-aminoproline isolated in the alkaline hydrolysis of guanidinoproline has been determined by means of ORD data and DAO oxidation. Assignement of trans geometry to the 3-aminoproline is based on the synthesis of both the cis and trans 3-aminoprolines.

Condensation of 1,4-diacetylpiperazine-2,5-dione with aldehydes has been applied to the synthesis of albonoursin and unsymmetrical 3,6-diarylidenepiperazine-2,5-diones. The reaction has been extended to 1,4-diacetyl-3,6-dimethylpiperazine-2,5-dione, which gives derivatives of 2-methyl-3- phenylserine. The mechanism and stereochemistry are discussed; cis 1-acetyl-3-isobutylidene- piperazine-2,5-dione has been isolated.