REACTIONS OF P-NITROBENZYL HALIDES WITH DIALKYL PHOSPHITE ANIONS IN DIMETHYL-SULFOXIDE

The reactions of p-O2NC6H4CH2Cl with (RO)(2)PO- in Me2SO with R = Me, Et, Pr, Bu, CF3CH2, i-Pr or Ph involve the formation of p-O2NC6H4CH2P( O) (OR)(2) by S(N)2 substitution followed by a further S(RN)1 p-nitro- benzylation of p-O2NC6H4CH[P(O)(OR)(2)](-) and p-O2NC6H4C(CH(2)C(6)H(4 )No2-p)[P(O) (OR)(2)](-). With p-O2NC6H4CH2Br, the reactions proceed m ainly to form p-O2NC6H4CH2-, which undergoes reaction with p-O2NC6H4CH 2Br to form p-O2NC6H4CH2CH2C6H4NO2-p. Halophilic reaction of (RO)(2)PO - with p-O2NC6H4CH(CH3)X (X = Cl, Br) leading to the bibenzyl is the p referred reaction course. Reactions of (RO)(2)PO- or p-O2NC6H4CH[P(O)( OR)(2)](-) with p-O2NC6H4CH2X in Me2SO do not form significant amounts of p-O2NC6H4CHX- that would yield p-O2NC6H4CH = CHC6H4NO2-p. However, p-Cl-C6H4CH[P(O)(OEt)(2)](-) readily abstracts the benzylic proton fr om p-O2NC6H4CH2X to form the stilbene, although p-O2NC6H4CH2Br reacts with p-O2NC6H4-CH[P(O)(OR)(2)](-) to form p-O2NC6H4CH(CH2C6-H4NO2-p)P( O)(OR)(2) in a reaction mixture not inhibited by (t-Bu)(2)NO.. (C) 199 8 John Wiley & Sons, Inc.