Department of Chemistry, National Institute of Technology Warangal, Warangal, Telangana-506004, India.
Org Biomol Chem. 2022 Jan 26;20(4):808-816. doi: 10.1039/d1ob02284a.
A transition-metal and hydride-free reductive aldol reaction has been developed for the synthesis of biologically active 3,3'-disubstituted oxindoles from isatin derivatives using rongalite. In this protocol, rongalite plays a dual role as a hydride-free reducing agent and a C1 unit donor. This transition metal-free method enables the synthesis of a wide range of 3-hydroxy-3-hydroxymethyloxindoles and 3-amino-3-hydroxymethyloxindoles with 79-96% yields. One-pot reductive hydroxymethylation, inexpensive rongalite ( $0.03/1 g), mild reaction conditions and short reaction time are some of the key features of this synthetic method. This protocol is also applicable to gram scale synthesis.
一种过渡金属和氢化物免费的还原羟醛反应已经被开发出来，用于使用连二亚硫酸钠从色胺衍生物合成具有生物活性的 3,3'-二取代的氧吲哚。在这个方案中，连二亚硫酸钠扮演了双重角色，既是无氢还原剂，又是 C1 单元供体。这种无过渡金属的方法能够合成广泛的 3-羟基-3-羟甲基氧吲哚和 3-氨基-3-羟甲基氧吲哚，产率为 79-96%。一锅还原羟甲基化、廉价的连二亚硫酸钠（$0.03/1 g$）、温和的反应条件和短的反应时间是这种合成方法的一些关键特点。该方案也适用于克级规模的合成。
