Catalytic Asymmetric Diamination of Styrenes

Abstract

An enantioselective catalytic vicinal diamination of styrenes is reported, which proceeds under entirely intermolecular reaction control. It relies on a chirally modified aryliodine(I) catalyst and proceeds within an iodine(I/III) manifold with conventional 3-chloroperbenzoic acid as terminal oxidant. An environmentally benign solvent combination not only adds to the attractiveness of the process, but also slows down the rate of the undesired background reaction. A total of 30 examples are presented, which consistently provide high enantiomeric excesses in the range of 91-98%.

Catalytic Asymmetric Radical Diamination of Alkenes

“…[1][2][3][4][5][6][7][8][11][12][13] In this regard, catalytic asymmetric diamination of unactivated alkenes with transition-metal or aryliodine(I) catalysts represents a straightforward and highly attractive method for creating such useful vicinal diamine scaffolds, given the facile accessibility of alkene starting materials. [14][15][16][17][18][19][20][21][22][23][24][25] However, the amine introduced by these asymmetric catalytic systems has to be masked by electron-withdrawing protecting groups, and direct incorporation of free alkylamine has so far remained elusive (Scheme 1A).…”

“…Two major factors have contributed to the lack of development of asymmetric alkene diamination with protection-free alkylamine. [14][15][16][17][18][19][20][21][22][23][24][25] On the one hand, the high affinity of a strongly Lewis-basic alkylamine for transition metal could lead to the formation of stable amine-metal complexes, thus resulting in poisoning of transition-metal catalysts. On the other hand, protection-free alkylamine is susceptible to oxidation under reported oxidative diamination reaction conditions.…”

“…On the other hand, protection-free alkylamine is susceptible to oxidation under reported oxidative diamination reaction conditions. [14][15][16][17][18][19][20][21][22][23][24][25] As a result, successful diamination of unactivated alkenes typically requires adequate electron-withdrawing protecting groups to suppress undesired strong ligation and amine oxidation, making these methods indirect for free amine synthesis and inconvenient for subsequent amine transformation (Scheme 1A).…”

Enantioselective Iodine(I/III) Catalysis in Organic Synthesis

“…Suitable conditions for the desired iodine(I/III) redox catalysis employed 3‐chloroperbenzoic acid ( m CPBA) as terminal oxidant, which in the optimized MTBE/HFIP solvent combination showed only negligible background epoxidation. In this way, the reaction proceeded with excellent enantioselectivity of up to 98% ee for terminal and internal styrenes (Scheme ) . This protocol pioneers enantioselective catalytic diamination of alkenes under intermolecular reaction control.…”

Hypervalent Iodine Reagents by Anodic Oxidation: A Powerful Green Synthesis

“…Hypervalent iodine reagents are widely used in modern organic synthesis . These reagents have tremendous synthetic applications, including difunctionalization of olefins and cyclopropanes, oxidative couplings, phenol dearomatizations, oxidative formation of heterocycles, aminations, halogenations, arylations, and rearrangements . In addition, a wide range of stereoselective transformations was achieved with high degree of stereocontrol using chiral hypervalent iodine reagents and catalytic systems of chiral iodoarenes and terminal oxidants .…”