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Page 6 of 11 Ji et al. Chem Synth 2022;2:17 https://dx.doi.org/10.20517/cs.2022.27

a a
Scheme 4. Scope of allylic sulfones . Unless otherwise noted, the reaction was conducted with 2 (0.2 mmol), 3a (0.2 mmol), 4a
(0.1 mmol), Rb CO (0.3 mmol), (R)-1a (0.012 mmol) and Pd dba (0.004 mmol) in MTBE (2 mL) at 0 ºC for 48 h under Ar. Isolated
2 3 2 3
b
c
yields are shown. The er values were determined by SFC. The reaction was performed at 10 ºC. Cs CO was used instead of Rb CO .
2 3 2 3
a SO Py group did not give the desired product (5ac), presumably because the pyridine group strongly
2
coordinated with the palladium to suppress the reaction. Additionally, the use of alkyl groups, such as
benzyl and tertiary butyl groups, instead of the phenyl group resulted in significant decreases in yield and
enantioselectivity (5ad-5ae). From these data, it is evident that the sulfone group was a vital aspect of
obtaining enantioselectivity and reactivity control. To our delight, allyl sulfonates were also suitable for this
reaction. The products 5af-5ah were always obtained in moderate yields with high enantioselectivities. As
expected, allyl sulfonamide suppressed the transformation.

Because chiral β,β-diaryl sulfones can be readily transformed into bioactive pharmaceutical molecules such
as (R)-CDP-840 and (R)-MCF-7 [33,34] , the extension of this catalytic system to the 1,1-diarylation of vinyl
sulfones was investigated. The desired product 7a was obtained in a 67% yield and with 95:5 er from the
reaction of vinyl sulfone 6a, 4-methoxybenzene diazonium salt 3a and phenylboronic acid 4a, using Cs CO
3
2
instead of Rb CO [Scheme 5]. Following this, a number of arylboronic acids were applied to the reaction
3
2
and the corresponding products were obtained in moderate yields with high enantioselectivities (7b-7f). It is
of note that ortho-tolylboronic acid was also suitable for this protocol and gave product 7e in 45% yield and
96:4 er. Phenyl aryldiazonium salt was employed in this reaction and product 7g was obtained in 45% yield
and 93.5:6.5 er. The absolute configuration of (S)-7g was determined by comparison with optical rotation
data for the reported literature . Likewise, the product 7h was obtained in 30% yield with 96:4 er using
[26]
vinyl sulfonate as the substrate. Finally, product ent-7a was produced in moderate yield with good