Stereospecific and Stereoselective Suzuki–Miyaura Cross-Coupling Reactions - New Trends in Cross-Coupling: Theory and Applications - page 538

Interestingly, the reaction was highly sensitive to chirality at sulfur, such that
the diastereomer of 113 was unreactive.

(11 : 26)

113

114

Following on this work, He and Falck described the stereospecific Suzuki-
Miyaura coupling of a-cyanotriflates 115. 81 As shown in eqn (11.27), boronic
acids couple readily with these substrates under mild conditions with high
levels of enantiospecificity. Again, the reaction proceeds with inversion of
configuration.

(11 : 27)

115 116

Building on these precedents and those of racemic couplings of benzylic
carbonates, 82 Jarvo and co-workers demonstrated that stereodefined alkyl
ethers could serve as useful substrates in Kumada-Corriu coupling [eqn
(11.28)]. 83 As shown below, the reaction proceeds via Ni catalysis and the
presence of a p-extended aromatic in the electrophile is critical. However,
considering the wide variety of enantiomerically enriched alcohols that can
be easily prepared, this method is an extremely important advance in the
area of stereospecific coupling of chiral nucleophiles. In subsequent work,
the nature of the ether substituent was shown to play a significant role, such
that by employing chelating groups such as the ethylene glycol derivative in
117b, the scope of the reaction was widened to include aryl Grignard re-
agents. 84,85 This is important since it permits the synthesis of enantio-
merically enriched triarylmethanes, which, as previously noted, are dicult
to prepare by other methods. As in the other examples described to date, the
reaction proceeded with inversion of configuration.

(11 : 28)

117a, b 118a, b

This reaction was later expanded to include organozinc nucleophiles, 86 but
more relevant to the topic of this chapter, this same concept has also been
applied to the Suzuki-Miyaura reaction of chiral alcohol-derived electrophiles.
In 2013, Jarvo's group demonstrated that a variety of enantioenriched elec-
trophiles could participate in the Ni-catalyzed Suzuki-Miyaura reaction with
neopentylboronic esters. 87 Remarkably, by switching the nature of the ligand
on Ni, the reaction could be made to proceed with high levels of inversion or