Stereoselective Oxidative Rearrangement of Disubstituted Unactivated Alkenes Using Hypervalent Iodine(III) Reagent

Abstract

The stereoselective oxidative rearrangement of disubstituted unactivated olefins has been achieved using a hypervalent iodine(III) reagent. The aryl group undergoes 1,2migration to give tert-α-arylated aldehydes (as acetals). The preparation of these aldehydes/acetals, especially containing a tert-benzylic stereocenter, has remained challenging. This migration-based method provides a complementary approach over the known α-substitution-based methods for accessing this class of molecules.

Catalyst-Substrate Helical Character Matching Determines the Enantioselectivity in the Ishihara-Type Iodoarenes Catalyzed Asymmetric Kita-Dearomative Spirolactonization

“…Given that the stabilizing π···π interaction presents only in the transition state leading to the major R enantiomer of the product, strengthening this interaction would lead to an increase in enantioselectivities. Inspired by the recent work of Houk and co-workers that fluorination of the π system could enhance the stacking interactions, we designed two new catalysts, ArI-4 and ArI-5 (Figure a). Our calculations show that the π···π interaction in the favored transition states for ArI-4 and ArI-5 are strengthened according to their shortened distance as compared with that for ArI-1 (Figure b).…”

Catalytic stereoselective synthesis involving hypervalent iodine-based chiral auxiliaries

“…112 The reaction begins with the alkoxylation of In 2020, Tiwari and coworkers reported enantioselective hypervalent iodine(III)-catalyzed oxidatve rearrangement in disubstituted non-activated alkene 114 involving 1,2-aryl group migration (Scheme 45). 113 The catalytic system comprises chiral hypervalent iodine(III) reagent 164 (20 mol%) as the catalyst, mCPBA as the stoichiometric oxidant, and Yb(OTf ) 3 as the additive. Using optimized reaction conditions, chiral rearranged product 165 was isolated in 27% yield with up to 92% ee.…”

Progress in organocatalysis with hypervalent iodine catalysts

“…In 2020, Tiwari and co-workers reported an iodine( iii )-catalysed enantioselective 1,2-tolyl group migration with geminal diacetoxylation of aromatic alkene 342 . 196 The reaction was performed at low temperature with the rearranged product 344 obtained in 27% yield with up to 92% ee (Scheme 100). The catalytic system involved 20 mol% chiral iodine( iii ) catalyst 343 and m CPBA in CHCl 3 : AcOH (1 : 1).…”