The Chemistry of Borylstannanes: Oxidative Addition to Palladium Species and Its Application to Palladium-Catalyzed Borylstannation of Alkynes

cis addition of the borylstannanes Me 3 SnB[NMe(CH 2 CH 2 )NMe] ( 1 ) and Me 3 SnB(NEt 2 ) 2 ( 4 ) across alkynes was efficiently catalyzed at room temperature or 80 °C by Pd(PPh 3 ) 4, Pd(dba) 2, Cl 2 Pd(PPh 3 ) 2, or Me 2 Pd[PMe 2 (CH 2 CH 2 )PMe 2 ] to give (β-stannylalkenyl)boranes in high yields. Treatments of 1 with Me 2 Pd[PMe 2 (CH 2 CH 2 )PMe 2 ] and of 4 with cis -Me 2 Pd(PPh 2 Me) 2 gave [{MeN(CH 2 CH 2 )MeN}B](Me 3 Sn)Pd[PMe 2 (CH 2 CH 2 )PMe 2 ] ( 5 ) and [(Et 2 N) 2 B](Me 3 Sn)Pd(PPh 2 Me) 2 ( 6 ), respectively, with the former characterized by X-ray analysis. Complex 5, when treated with 1-octyne, formed the corresponding (β-stannyl-1-octen-1-yl)borane and could catalyze the addition reaction of 1 with 1-octyne.