Cyclic sulfonium salts are a class of heterocyclic compounds containing a tetravalent sulfur atom.Due to their inherent electronic deficiency,they exhibit excellent thermodynamic stability and high reactivity,and thus play a significant role in organic synthesis.In recent years,the ring-opening reactions of cyclic sulfonium salts have garnered significant atten-tion for their application in the construction of sulfur-containing compounds,particularly through nucleophilic and free radical type ring-opening reactions.These reactions not only provide new approaches for the synthesis of diverse sulfur-containing compounds but also broaden their potential applications in drug development and functional materials.The latest research progress of ring-opening reactions of cyclic sulfonium salts is summarized,focusing on the formation reactions of C-C bond and C-heteroatom bond in nucleophilic and free radical type ring-opening reactions.The substrates scope and reaction mechanisms are discussed in detail,and the potential value of these methodologies in the synthesis of sulfur-containing com-pounds is also discussed.
Over the past decade,photocatalysis has emerged as one of the frontiers in organic chemistry,attracting tremendous interest from the synthetic community.Compared to traditional methods,photocatalytic reactions offer advantages such as mild conditions,high functional group tolerance and unique reactivity and selectivity.As an important area of photocatalysis,the transformation of imines is undergoing continuous advancements.Under photocatalytic conditions,the reactivity of imines is reshaped,allowing them to undergo single-electron reduction to form α-aminoalkyl radicals-a process that can even reverse their polarity,enabling them to act as carbon nucleophiles.N-Heterocycles and amines are among the most prevalent and important organic compounds,which are found in numerous alkaloids and pharmaceutical molecules.Therefore,the conversion of imine compounds to amines under photocatalytic conditions has introduced new methodologies to solve important problems in the synthesis of drugs and related fields,which were hardly achieved by traditional synthetic strategies.This review summarized the research progress on the photocatalytic synthesis of amines from imines viaα-aminoalkyl radicals,with a focus on selectivity and functional group tolerance.
酰胺键广泛存在于小分子、多肽及蛋白质中(Scheme 1),其高效构建始终是合成化学与化学生物学中的核心问题之一[1].尽管酰胺键构筑的方法已得以发展,但在温和、水相条件下,由低活化态底物(如醛或醇)直接实现选择性酰胺化仍具挑战性.现有策略多依赖高活化酰基试剂或复杂酶体系(Scheme 2),限制了其在绿色与生物相容条件下的应用前景[2].
A catalytic system comprising a readily available chiral binaphthyl-based P-N-O tridentate ligand and iridium has been developed for the highly efficient asymmetric hydrogenation of simple aromatic ketones. Using prochiral aromatic ketones as substrates, this system gives the corresponding chiral alcohols in up to >99% yield and 97% enantioselectivity under mild conditions. Systematic optimization of reaction conditions revealed that (R)-2-(((2'-(diphenylphosphaneyl)-[1,1'-binaphthalen]-2-yl)amino)methyl)phenol (L1) as the ligand, Ba(OH)2 as the base additive, and 95% (phi) ethanol as the solvent were critical for achieving excellent performance. The catalytic system exhibits good substrate generality, being applicable to various aromatic ketones and heteroaromatic ketones with different substituents. Furthermore, this method was successfully applied to the synthesis of (S)-3-(dimethylamino)-1-(thiophen-2-yl)propan-1-ol, a key chiral intermediate of the antidepressant (S)-duloxetine, affording the target product with 98% yield and 90% ee, which fully demonstrates its great application potential in practical synthesis.
