Transmetalation of Alkylboranes to Palladium in the Suzuki Coupling Reaction Proceeds with Retention of Stereochemistry

Abstract

Deuterium-labeling experiments demonstrate that the transmetalation step of the Suzuki coupling reaction of alkylboranes and alpha-iodoenones proceeds with retention of stereochemistry.

At the Forefront of the Suzuki–Miyaura Reaction: Advances in Stereoselective Cross-Couplings

“…The authors proposed that the silver oxide played a role in accelerating a potentially slow transmetallation step. It was found that this process proceeded with good stereoretention, presumably via 4-membered transition state 39, as previously proposed by Soderquist [64] Woerpel [63] (see Sect. 3.2).…”

“…The stereochemistry of the transmetallation step in the Suzuki-Miyaura coupling of aryl and alkenyl halides with sp 3 organoboranes was independently studied by Woerpel [63] and Soderquist [64], and more recently by Jarvo [65]. Deuteriumlabelled substrates 30 and 33 were subjected to the coupling conditions and revealed a stereoretentive transmetallation step, leading to products 32 and 34, respectively (Scheme 8).…”

Synthesis of chiral heterocycles by ligand-controlled regiodivergent and enantiospecific Suzuki Miyaura cross-coupling

“…Because the C-B bond of A is 'locked' on a specific face of the allyl unit, the reaction is enantiospecific regardless of the three pathways described above. The observed retention of configuration is the outcome of a stereoretentive transmetallation followed by a stereoretentive reductive elimination 44,45 . Whereas the occurrence of enantiomeric erosion is possible in reactions of chiral p-allyl palladium complexes 46,47 , it is observed only to a minimal extent in these sp 3 -sp 2 cross-couplings.…”

The B-Alkyl Suzuki-Miyaura Cross-Coupling Reaction: Development, Mechanistic Study, and Applications in Natural Product Synthesis

“…Independent studies by the groups of Soderquist [33] and Woerpel [34] revealed that transmetalation (RÀB 3RÀPd) occurs with retention of stereochemistry. Both groups used an NMR spectroscopic technique that takes advantage of the preference of bulky substituents on 1,2-disubstituted ethanes to adopt an antiperiplanar conformation.…”