ALKYLATION OF DIMETHYLAMINOBIS(TRIFLUOROMETHYL)BORANE BY 1-ALKENES

Dimethylaminobis(trifluoromethyl)borane, (CF3)2BNMe2 (A), undergoes B-alkylation on treatment with 1-alkenes of the general formula (R1CH2)(R2)C=CH2 to yield triorganoboron adducts Me2(H)N-B(CF3)2CH2(R2)C=CHR1 (R1 = H, R2 = Me(I); R1 = H, R2 = CH2(CF3)2B-NHMe2 (II); R1 = Me, R2 = Et (III); R1 = H, R2 = CH2((t)Bu) (IV): R1 = H, R2 = Ph (V); R1 = H, R2 = CH=CMe2 (VI); R1 = Ph, R2 = H (VII); R1 = (n)Pr, R2 = H (VIII); R1 = (i)Pr, R2 = H (IX)). In contrast. monosubstituted ethene derivatives (R2)CH=CH2 (R = (s)Bu, Ph, Mes, Me3Si, Et3Si) react with A to form the corresponding methylmethyleneimine boron adducts H2C=N(Me)-B(CF3)2CH2CH2R2 (X, XII-XV). With ((t)Bu)(Me)C=CH2, A undergoes both types of reaction, yielding a 1/4 mixture of Me2(H)N-B(CF3)2CH2(tBu)C=CH)2 (XIa) and H2C=N(Me)-B(CF3)2CH2CH(Me)(tBu) (XIb). Whereas I-IX and XIa are formed by an ene-type reaction, X and XIb-XV result from a shift of a hydride from the dimethylamino group to the alkylating substituent. The novel boranes have been characterized by elemental analysis and multinuclear NMR, IR and mass spectroscopy.