Alkenes, with acids thiiranes

Of trialkyl phosphites the most frequently used is triethyl phosphite (EtO)3P (M.W. 166.16, b.p. 156°, density 0.969) which combines with sulfur in thiiranes [291, 294] and gives alkenes in respectable yields. In addition, it can extrude sulfur from sulfides [295], convert a-diketones to acyloins [296], convert a-keto acids to a-hydroxy acids [297], and reduce nitroso compounds to hydroxylamines [298] Procedure 47, p. 111). 

The soft donor property of S atom is manifested in sulfur extrusion from thiiranes by carbenes and other soft Lewis acids such as iodine (82), and iodo-methane (83) thiiranes assume the role of acceptors when reacting with phosphines (84, 85). Oxiranes, on the contrary, do not react with phosphines except under drastic conditions whereby a mixture of isomeric alkenes are produced. 

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