Rhodium-catalyzed conjugate addition of arylindium reagents to α,β-unsaturated carbonyl compounds

Static to inducibly dynamic stereocontrol: The convergent use of racemic β-substituted ketones

The synthesis of stereochemically complex molecules in the pharmaceutical and agrochemical industries requires precise control over each distinct stereocenter, a feat that can be challenging and time consuming using traditional asymmetric synthesis. Although stereoconvergent processes have the potential to streamline and simplify synthetic routes, they are currently limited by a narrow scope of inducibly dynamic stereocenters that can be readily epimerized. Here, we report the use of photoredox catalysis to enable the racemization of traditionally static, unreactive stereocenters through the intermediacy of prochiral radical species. This technology was applied in conjunction with biocatalysts such as ketoreductases and aminotransferases to realize stereoconvergent syntheses of stereodefined γ-substituted alcohols and amines from β-substituted ketones.

Triorganoindium Reagents in Rh-Catalyzed C⁻H Activation/C⁻C Cross-Coupling Reactions of 2-Arylpyridines

The activation of C–H bonds through catalytic reactions using transition metals is an important challenge in organic chemistry in which the intermediates are related to those produced in the classical cross-coupling reactions. As part of our research program devoted to the development of metal-catalyzed reactions using indium organometallics, a protocol for the C–H activation and C–C coupling of 2-arylpyridines with triorganoindium reagents under Rh(I) catalysis is reported. Under the optimized conditions, we found that Me₃In and Ar₃In reagents reacted with 2-arylpyridines and related compounds in the presence of Rh(PPh₃)₃Cl, in PhCl/THF (9:1), at 120 °C for 48 h, to afford the ortho-coupling products in moderate to good yields. The nitrogen atom in the pyridine ring acts as a directing group to assist the functionalization at the ortho position of the aryl group forming a new C–C bond at this position.

Activation of Marginally Reactive Boron Enolates by MeLi for the Formation of Enol Phosphates and Synthesis of the Δ(9)-THC Intermediate

The addition of MeLi to boron enolates produced by the 1,4-addition of Ar2Cu(CN)Li2 to BF3·OEt2-activated enones was followed by the reaction with ClP(O)(OEt)2 to afford the corresponding enol phosphates in moderate to good yields. The scope of this method was examined with sterically hindered or electronically biased enones and/or reagents. This activation of boron enolates was successfully applied to the synthesis of the methyl ether of Δ(9)-tetrahydrocannabinol.

Tandem hydrogenation and condensation of fluorinated α,β-unsaturated ketones with primary amines, catalyzed by nickel

A simple homogeneous catalytic system based on nickel phosphine complexes has been developed for the transfer hydrogenation and condensation of α,β-unsaturated ketones to yield saturated ones and saturated imines using primary amines as hydrogen donors.

Indium-catalyzed intramolecular hydroarylation of aryl propargyl ethers

Indium(iii) halides are efficient and selective catalysts for the intramolecular hydroarylation of aryl propargyl ethers.

Arylation of aldehyde homoenolates with aryl bromides

A mild palladium catalyzed coupling of reactive aldehyde homoenolates with aryl bromides is described. Aldehyde homoenolates are generated by ring opening of cyclopropanols via a C-C cleavage step. The coupling generates aldehyde products at room temperature in 59-93% yield.