Carbon-boron bonds, reductive elimination

This reaction typifies the two possibilities of reaction routes for M-catalyzed addition of an S-X (or Se-X) bond to alkyne (a) oxidative addition of the S-X bond to M(0) to form 94, (b) insertion of alkyne into either the M-S or M-X bond to provide 95 or 96 (c) C-X or C-S bond-forming reductive elimination to give 97 (Scheme 7-21). Comparable reaction sequences are also discussed when the Chalk-Harrod mechanism is compared with the modified Chalk-Harrod mechanism in hydrosily-lations [1,3]. The palladium-catalyzed thioboratiori, that is, addition of an S-B bond to an alkyne was reported by Miyaura and Suzuki et al. to furnish the cis-adducts 98 with the sulfur bound to the internal carbon and the boron center to the terminal carbon (Eq. 7.61) [62]. 

The arylation of carbon-hydrogen bonds in polycyclic aromatic hydrocarbons, using aryl boron compoimds or aryl silanes, may be achieved with a palladium acetate/o-chloranil catalyst. The Suzuki-Miyaura reaction involves palladium-catalysed coupling of an arylboronic acid with an aryl hahde in the presence of base. After oxidative addition of palladium to the hahde, reaction with base may form intermediates such as (105). Transmetalation with the boronic acid followed by reductive elimination yields... 

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