Stereocontrolled Synthesis of Phosphoproline Analogues Containing a -Fused Octahydroindole Bicyclic System.

Herein we report for the first time the diastereoselective synthesis of (2,3a,7a)- and (2,3a,7a)-octahydroindole-2-phosphonic acid (Oic -fused stereoisomers) from diethyl ()- and ()-phosphopyroglutamate derivative. The key steps of this procedure are the ruthenium tetroxide oxidation of enantiomerically pure diethyl ()- and ()-phosphoprolinate obtained through Katritzky's benzotriazole-oxazolidine methodology, a highly diastereoselective successive double 4,5-diallylation of diethyl ()- and ()-phosphopyroglutamate with allyl bromide and allyltrimethylsilane with a -addition mode, and a ring-closing metathesis with Grubbs' first-generation ruthenium catalyst.