Alkylation of dimethylaminobis(trifluoromethyl)borane by 1-alkenes

Article abstract of DOI:10.1016/0022-328X(93)83310-R

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(^tBu) (IV); R¹ = H, R² = Ph (V); R¹ = H, R² = CH=CMe2 (VI); R¹ = Ph, R² = H (VII); R¹ = ⁿPr, R² = H (VIII); R¹ = ⁱPr, R² = H (IX)).In contrast, monosubstituted ethene derivatives (R²)CH=CH2 (R = ^sBu, Ph, Mes, Me3Si, Et3Si) react with A to form the corresponding methylmethyleneimine boron adducts H2C=N(Me)-B(CF3)2CH2CH2R² (X, XII-XV).With (^tBu)(Me)C=CH2, A udergoes both types of reaction, yielding a 1;4 mixture of Me2(H)N-B(CF3)2CH2(⁵tBu)C=CH2 (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.