Ruthenium-Catalyzed Homo and Cross Metathesis Reactions of Alkenylpolyboranes: New Routes to Functional <i>o</i>-Carborane and Decaborane Derivatives

Abstract

Both 1-(CH2CHCH2)-1,2-C2B10H11 (1) and 6-[CH2CH(CH2)4]-B10H13 (2) undergo homometathesis and cross metathesis reactions in the presence of the Cl2Ru(CHPh)(PCy3)L, L = PCy3 (I) or H2IMes (II), Grubbs catalysts. According to the Grubbs classification, 1 is a type-II olefin for I and a type-I olefin for II and 2 is a type-I olefin for both the I and II catalysts. Homometathesis of 1 produces the olefin-bridged compound 1,1‘-(CH2CHCHCH2)-(1,2-C2B10H11)2 (3), while the cross metathesis reactions of 1 with a variety of olefins are efficient, high-yield routes to functional o-carborane 1-R-1,2-C2B10H11 derivatives, including R = C6H5CH2CHCHCH2− (4), C6H5CHCHCH2− (5), CH3C(O)OCH2CHCHCH2− (6), HOCH2CHCHCH2− (7), ClCH2CHCHCH2− (8), C6H5CH2OCH2CHCHCH2− (9), CH3(CH2)3CHCHCH2− (10), CF3C(O)OCH2CHCHCH2− (11), CH3C(O)(CH2)2CHCHCH2− (12), t-C4H9OC(O)NHCH2CHCHCH2− (13), NC(CH2)3CHCHCH2− (14), and {[(CH3)4C2O2]BCH2CHCHCH2}− (15). Deboronation of 1,1‘-(CH2CHCHCH2)-(1,2-C2B10H11)2 (3) with CsF affords the olefin-bridged bis(dicarbollide) salt 2Cs+·[7,7‘-(CH2CHCHCH2)-7,8-(C2B9H11)2]2- (16). Similar reactions of 1-[CH3(CH2)3CHCHCH2]-1,2-C2B10H11 (10) with CsF and tetrabutylammonium fluoride generate the Cs+ (17) and [N(C4H9)4]+ (18) [7-CH3(CH2)3CHCHCH2-7,8-C2B9H11]- salts, respectively. Homometathesis of 2 affords 6,6‘-[(CH2)4CHCH(CH2)4]-(B10H13)2 (19), and its cross metathesis reactions with functional olefins yield a range of functionalized decaborane derivatives 6-R-B10H13 (R = C6H5CH2CHCH(CH2)4− (20), CH3C(O)OCH2CHCH(CH2)4− (21), C6H5CH2OCH2CHCH(CH2)4− (22), ClCH2CHCH(CH2)4− (23), CH3(CH2)3CHCH(CH2)4− (24), CF3C(O)OCH2CHCH(CH2)4− (25), C6H5CHCH(CH2)4− (26), CH3C(O)(CH2)2CHCH(CH2)4− (27), CH3CH2OCH2CHCH(CH2)4− (28), and CH3OC(O)CHCH(CH2)4− (29)). Cross metathesis of 1 with 2 produces 1-[1-(1,2-C2B10H11)]-CH2CHCH(CH2)4-7-(6-B10H13) (30), having o-carborane and decaborane cages linked by an alkenyl bridge.