Copper-Catalyzed Borylative Couplings with C-N Electrophiles.

Copper-catalyzed borylative multicomponent reactions (MCRs) involving olefins and C-N electrophiles are a powerful tool to rapidly build up molecular complexity. The products from these reactions contain multiple functionalities, such as amino, cyano and boronate groups, that are ubiquitous in medicinal and process chemistry programs. Copper-catalyzed MCRs are particularly attractive because they use a relatively abundant and non-toxic catalyst to selectively deliver high-value products from simple feedstocks such as olefins. In this Minireview, we explore this rapidly emerging field and survey the borylative union of allenes, dienes, styrenes and other olefins, with imines, nitriles and related C-N electrophiles.

Process Design and Optimization in the Pharmaceutical Industry: A Suzuki-Miyaura Procedure for the Synthesis of Savolitinib.

A multidisciplinary approach covering synthetic, physical, and analytical chemistry, high-throughput experimentation and experimental design, process engineering, and solid-state chemistry is used to develop a large-scale (kilomole) Suzuki-Miyaura process. Working against clear criteria and targets, a full process investigation and optimization package is described highlighting how and why key decisions are made in the development of large-scale pharmaceutical processes.

Modular Synthesis of Constrained Ethyl (cEt) Purine and Pyrimidine Nucleosides.

A modular and scalable approach to pyrimidine- and purine-containing constrained ethyl (cEt) nucleosides is demonstrated. Minimizing stereochemical adjustments and protecting group manipulations, diacetone glucose is converted to two representative cEt nucleosides via a functionalized, common intermediate. The retrosynthetic approach to this complex class of drug precursors offers clear benefits over existing routes based on step count and efficiency.

A furan Diels-Alder cycloaddition approach to scyphostatin analogues.

The synthesis of two diastereoisomers of the epoxycyclohexenone core of scyphostatin, a naturally occurring sphingomyelinase inhibitor, has been achieved via a common oxabicyclic intermediate. The diastereomeric intermediates are accessed by stereodivergent oxidative functionalisation processes, followed by a Lewis acid mediated ring opening rearrangement reaction.

Catalytic asymmetric synthesis of acyclic arrays by tandem 1,4-addition-aldol reactions.

Herein, we report efficient acyclic stereocontrol in tandem 1,4-addition-aldol reactions triggered by catalytic asymmetric organometallic addition. Grignard reagents add to alpha,beta-unsaturated thioesters in a 1,4-fashion and the resulting magnesium enolates are trapped with aromatic or aliphatic aldehydes. The process provides a range of tandem products bearing three contiguous stereocenters with excellent control of relative and absolute stereochemistry. The various diastereomeric products have been fully characterized using single-crystal X-ray analysis and the origins of stereocontrol in this tandem protocol are discussed. The versatility and efficiency of this methodology are demonstrated in the first catalytic asymmetric synthesis of (-)-phaseolinic acid with 54% overall yield via a short and concise route.

An asymmetric nitro-Mannich reaction applicable to alkyl, aryl, and heterocyclic imines.

[reaction: see text] A protocol for the enantioselective nitro-Mannich coupling between alkyl, aryl, and heterocyclic p-methoxybenzylimines and trimethylsilylnitropropanate catalyzed by a chiral tBu-BOX Cu(II) catalyst is described. It uses the lowest reported loading of commercially available metal catalyst and chiral ligand, and gives the highest yields and selectivities for a broad substrate range including nonaromatic aldimines. The resultant beta-nitroamines are obtained in 70-94% enantiomeric excess in good yield and can be readily reduced to synthetically useful 1,2-diamines.

Scope and limitations of the nitro-Mannich reaction for the stereoselective synthesis of 1,2-diamines.

The acetic acid-promoted addition of lithium nitropropanate and the Lewis acid-catalyzed [Sc(OTf)3, Cu(OTf)2, or Ti(OiPr)4] addition of trimethylsilyl nitropropanate to a range of heteroaromatic and simple aliphatic aldimines gave anti-rich (approximately 3-19:1) beta-nitroamines in >95% yields as the kinetic products. It was found that a nonpolar N-imine protecting group was essential for reactivity with the o-methoxybenzyl (OMB) group giving better selectivities and yields than p-methoxybenzyl (PMB) or p-methoxyphenyl (PMP) in the Lewis acid-catalyzed addition reactions. Reduction with SmI2, treatment with COCl2, followed by OMB deprotection gave diastereomerically pure cis-imidazolidinones in 55-79% overall yield from imine. Preliminary results have shown that acetic acid can catalyze the reaction of N-OMB-benzylideneamine with nitropropane, used as solvent, to give the thermodynamically more stable syn-beta-nitroamine product.