Cyclic phosphonium salts alkaline hydrolysis

Preparation, properties and reactions of phosphonium salts TABLE 19. Stereochemistry of the alkaline hydrolysis of cyclic phosphoniums salts... 

Further examples in which pentacoordinate phosphorus intermediates are implicated are the reactions of phosphonium salts. The cyclic phosphonium salt (161) shows a rate enhancement of 1300 1 in alkaline hydrolysis relative to either its six-membered or acyclic analogues (65ACS931). Ring strain relief in going from (163) to (164) seems to account for the higher rate of formation of the favoured intermediate (163 see Scheme 19). 

We have simulated the steric course of the alkaline hydrolysis of chiral five- (12) and six- (13) membered cyclic phosphonium salts, whose reaction kinetics and product stereochemistries had been studied previously by Marsi and coworkers (14,15). For this purpose, we determined the absolute configuration of the phospholan-ium iodide (12), and the x-ray structures of the related phos-thorinanium salts, 4 and (13). 

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