Jean-François Pons

A Constrained Diketopiperazine as a New Scaffold for the Synthesis of Peptidomimetics

As a new scaffold for peptidomimetic synthesis, a highly constrained bifunctional diketopiperazine, 4, has been prepared by smooth N-alkylation with tert-butyl bromoacetate. As a first application, we describe herein the synthesis of new peptidomimetics of the Arg-Gly-Asp (RGD) sequence. The product 30, which shows a selective platelet-aggregation inhibiting activity, can be used as a lead for the preparation of more potent products.

Concurrency and Recovery for Typed Objects using a New Commutativity Relation

Transactional systems are based on two distinct transaction models: the update in place model (UIP) and the deferred update model (DU). When considering typed objects relative to concurrency, the expression of commutativity depends on the transaction model on which it is applied: backward commutativity for the UIP model and forward commutativity for the DU model. These two relationships cannot be compared with regard to the concurrency allowed between transactions, as the executions generated by each model are different. This paper combines backward and forward commutativity relations in a new relationship, named Forward-Backward commutativity. This relationship includes both previous ones and provides more concurrency than the union of both. Furthermore, the paper proposes a new concurrency and recovery protocol using this relation, based on biversion objects. Biversion objects are only needed during concurrent executions.