ENE-TYPE AND HYDRIDE-SHIFT REACTIONS OF THIOCARBONYL COMPOUNDS WITH (DIMETHYLAMINO)BIS(TRIFLUOROMETHYL)BORANE, (CF3)2BNME2

(Dimethylamino)bis(trifluoromethyl)borane, (CF3)2BNMe2 (A), reacts wit h thiocarbonyl compounds of the general formula R2C(S)CH2R1 to yield t he triorganoboron adducts (R2C(S)CHR1)(CF3)2B . NHMe2: R2 = NMe2; R1 = H (I), Me (II); R2 = OEt; R1 = H (111), Me (IV); R2 = SEt; R1 = H (V) . When R2 = SEt and R1 = Me, the thioenol derivative (MeHC=C(SEt)S)(CF 3)2B . NHMe2 (VI) is formed, while PhC(S)Me yields the analogous amine borane (H2C-C(Ph)S)(CF3)2 B . NHMe2 (VII). Compound V adds a second m olecule of A to form ((NHMe2 . (CF3)2B)HC=C(SEt)S)(CF3)2B . NHMe2 (VII I). Treatment of A with MeC(S)(t)Bu at - 40-degrees-C yields (H2C-C((t )Bu)S)(CF3)2 B . NHMe2 (IX) in an ene-type reaction. This rearranges a t 20-degrees-C by a unimolecular process to the methyl-methyleneimine stabilized borane (Me(tBu)C(H)S)(CF3)2B . N(CH3)=CH2 (X). The identiti es of the novel compounds have been confirmed by multinuclear NMR IR a nd mass spectrometry.