Topics in Current Chemistry (2020) 378:9
1 3
addition of 82 to a gold carbenoid intermediate generated from α-diazo esters 81.
The resulting enol intermediate 85 underwent a CPA-mediated asymmetric protonation. Hydrolysis of the imine products 86 produced γ-keto esters 84 in high
yields and with excellent enantioselectivities.
7 Miscellaneous
In 2014, Lu and Xiao reported a visible light-induced aerobic oxidation/semipinacol
rearrangement for efficient transformation of 2,3-disubstituted indoles 87 into chiral
2,2-disubstituted indolin-3-ones 88 (Scheme 23) [79]. Preliminary investigation of
asymmetric Ru(II) and CPA relay catalysis in this cascade reaction achieved moderate enantioselectivity (60% ee).
In 2014, Tan, Liu and coworkers [80] reported an asymmetric relay functionalization of unactivated alkene/C(sp
3
)-H bond enabled by a Cu/CPA relay catalytic system
(Scheme 24). Mechanistic studies revealed that the Cu(I) reduced the hypervalent iodine
Togni reagent to release a CF 3 radical, which initiated a radical reaction sequence,
including CF 3 radical addition to the alkene moiety, 1,5-hydrogen atom abstraction and
single-electron oxidation of α-amino radical, to give an imine intermediate. Subsequent
Scheme 23 Photocatalytic aerobic oxidation/semipinacol rearrangement sequence
Scheme 24 Enantioselective functionalization of C-H bonds based on 1,5-H shift
Reprinted from the journal
198
1 3
addition of 82 to a gold carbenoid intermediate generated from α-diazo esters 81.
The resulting enol intermediate 85 underwent a CPA-mediated asymmetric protonation. Hydrolysis of the imine products 86 produced γ-keto esters 84 in high
yields and with excellent enantioselectivities.
7 Miscellaneous
In 2014, Lu and Xiao reported a visible light-induced aerobic oxidation/semipinacol
rearrangement for efficient transformation of 2,3-disubstituted indoles 87 into chiral
2,2-disubstituted indolin-3-ones 88 (Scheme 23) [79]. Preliminary investigation of
asymmetric Ru(II) and CPA relay catalysis in this cascade reaction achieved moderate enantioselectivity (60% ee).
In 2014, Tan, Liu and coworkers [80] reported an asymmetric relay functionalization of unactivated alkene/C(sp
3
)-H bond enabled by a Cu/CPA relay catalytic system
(Scheme 24). Mechanistic studies revealed that the Cu(I) reduced the hypervalent iodine
Togni reagent to release a CF 3 radical, which initiated a radical reaction sequence,
including CF 3 radical addition to the alkene moiety, 1,5-hydrogen atom abstraction and
single-electron oxidation of α-amino radical, to give an imine intermediate. Subsequent
Scheme 23 Photocatalytic aerobic oxidation/semipinacol rearrangement sequence
Scheme 24 Enantioselective functionalization of C-H bonds based on 1,5-H shift
Reprinted from the journal
198