INSERION REACTIONS OF DIAZO COMPOUNDS WITH SOME SELENIUM(II) ELECTROPHILES

Article abstract of DOI:10.1016/0022-328X(85)88004-9

Benzene- and o-nitrobenzene-selenyl thiocyanate (1 and 2) reacted with diazomethane and several α-diazo esters to afford α-arylseleno isothiocyanates (5a-10a) and the isomeric thiocyanates (6b-8b) as the major and minor products, respectively.Analogous insertion reactions were observed with benzenesulfenyl thiocyanate (3) and benzeneselenenyl selenocyanate (4) to furnish phenylthiomethyl isothiocyanate (11), ethyl α-phenylthioisocyanoacetate (12) and phenylselenomethyl isoselelnocyanate (13), ethyl α-phenylseleno-α-isoselenocyanoacetate (14), respectively.N-(Phenylseleno)phthalimide formed insertion products N-(phenylselenomethyl)phthalimide (16) and ethyl α-phenylseleno-α-phthalimidoacetate (17)with diazomethane and ethyl diazoacetate, but effected elimination to the corresponding vinyl selenides, ethyl α-(phenylseleno)propenoate (18) and ethyl 2-phenylseleno-3-methyl-2-butenoate (19) when treated with diazo esters containing β-hydrogens.Compound 19 was similarly obtained from benzeneselenenyl iodide and the diazo ester.Attempts to effect selenoxide eliminations in compounds 7a-10a were unsuccessful.A new, efficient preparation of 1 from the metathesis of benzeneselenenyl chloride with trimethylsilyl isothiocyanate was developed.