The Expanding Utility of Rhodium‐Iminocarbenes: Recent Advances in the Synthesis of Natural Products and Related Scaffolds

Abstract

Rhodium-iminocarbenes that are derived from N-sulfonyl-1,2,3-triazoles have become an important class of reactive species and useful intermediates in organic synthesis. Over the last several years, many practical and versatile approaches involving rhodium-iminocarbene intermediates to synthetically challenging molecules (scaffolds) have been developed. This Minireview mainly summarizes the recent advance of rhodium-iminocarbene involved reactions in the synthesis of natural products and their related scaffolds by the end of 2017. Several applications in important pharmaceuticals are documented as well.

Synergistic Pd(0)/Rh(II) Dual Catalytic [6 + 3] Dipolar Cycloaddition for the Synthesis of Monocyclic Nine-Membered N,O-Heterocycles and Their Alder-ene Rearrangement to Fused Bicyclic Compounds

“…During our ongoing studies on dual-transition-metal catalysis, we envisioned that the monocyclic medium-sized N,O -heterocyclic moieties could be accessed by synergistic Pd(0)/Rh­(II) dual catalysis. Herein we report a novel Pd(0)/Rh­(II) dual catalytic strategy to enable [6 + 3] cycloadditions between vinylpropylene carbonates (VPCs) 1 and N -sulfonyl-1,2,3-triazoles 2 to furnish the monocyclic 1,4-oxazonines 3 . As depicted in Scheme B, the catalytically generated 1,6- and 1,3-dipole-equivalent intermediates, namely the zwitterionic alkoxy π-allyl Pd­(II) complex II and the α-imino Rh­(II) carbenoid III , respectively, undergo a [6 + 3] dipolar cycloaddition to result in nine-membered N,O -heterocyclic dienes 3 , which could then further undergo an unprecedented transannular Alder-ene rearrangement to afford the cis -fused [4.3.0] bicyclic compound 4 .…”

Rhodium-Catalyzed Denitrogenative Transannulation of N-Sulfonyl-1,2,3-triazoles with Glycals Giving Pyrroline-Fused N-Glycosides

“…16 Therefore, a direct and concise methodology for the selective synthesis of structure-diverse PFGs will greatly accelerate the development of new PFG functional molecules and pharmaceuticals. In view of the versatile synthons of glycals 17 and N-sulfonyl-1,2,3-triazoles, 18 we envisaged that the direct denitrogenative transannulation of glycals with Nsulfonyl-1,2,3-triazoles would provide a direct and reliable method for constructing various PFGs (Scheme 1a). Herein, we present an efficient and straightforward method for the stereoselective preparation of PFGs through a Rh-catalyzed denitrogenative transannulation of commercially available glycals and N-sulfonyl-1,2,3-triazoles (Scheme 1c).…”

Research Progress of 1,3,5-Triazinanes in the Synthesis of Nitrogen-Containing Heterocycles

“…2021 年, 王凯凯等 [64] 报道了无金属催化 合成四氮杂䓬103 的反应(Scheme 32). 亚胺叶立德 99 和 1,3,5-三嗪烷分别作为双原子和五原子合成子, 参与 N-磺酰基-1,2,3-三氮唑可通过铜催化炔-叠氮化物 的环加成反应顺利制得, 在适当的过渡金属催化剂作用 下, 可转化为 α-亚氨基金属卡宾, 因此引起了有机化学 工作者极大的研究兴趣 [65][66][67][68][69][70][71] . 鲍晓光等 [72] 报道了一种铑 催化三氮唑[2＋5]环化合成八氢嘌呤 105 骨架的方法 (Scheme 33).…”