Transition-metal-free C(sp³)–H/C(sp³)–H dehydrogenative coupling of saturated heterocycles with N-benzyl imines

Abstract

A unique transition-metal-free C(sp3)–H/C(sp3)–H dehydrocoupling of N-benzylimines with saturated heterocycles is presented using 2-azaallyl anions as super electron donors to initiate the generation of hydrogen atom abstracting aryl radicals.

C–H functionalization reactions enabled by hydrogen atom transfer to carbon-centered radicals

“…The latter adds to the in situ formed iminium salt B to afford after reduction by Ti(III) species 1,2-aminoalcohol derivatives 168a-c. More recently, Li, Zhang, Yang, Walsh and co-workers developed transition metal-free dehydrogenative crosscoupling of N-benzyl amines and saturated heterocycles (Scheme 43). 91 They have shown that 2-azaallyl anion A, generated by deprotonation of N-benzyl amines, can undergo SET to aryl iodide to form aryl radical and persistent 2-azaallyl radical B. Sterically protected sacrificial aryl radical undergoes intermolecular HAT at activated C(sp 3 )-H sites to form stabilized nucleophilic radical C, which recombines with persistent 2azaallylradical B to deliver the products 174a-d.…”

Analysis of the Relation between Coupled Sink and Purification Based on Hydrogen Network Integration

“…For the sink tie line lying below, between, and above the coupled sink and source, its HUA can be determined by Eqs. (2), (3), and (4), respectively . …”

“…Ng et al proposed the pinch‐based automated approach to target the minimum utility consumption of the property and concentration‐based conservation networks with regeneration/purification reuse. Liu et al developed a systematic method to identify the quantitative relationships among the hydrogen utility consumption and the purification feed and purified product , the limiting and optimal purification feed flow rate , the limiting and optimal purification feed and purified product purity , hydrogen recovery as well as optimization of flow rate and purity of the purification feed simultaneously . Zhang et al proposed the quality triangle rules and developed a graphic method for analyzing hydrogen utility consumption of the hydrogen network with purification.…”

“…No matter which parameter of the reactor and purifier changes, its effect is reflected by the variation of the composition and flow rate of the sink and source stream. Based on the graphical integration method of Liu et al and Mao et al , this work aims to analyze the relation between the coupled streams connecting to the hydrogen‐consuming reactor and purification, and develop a graphical method for evaluating their relation. First, the quantitative relationships between the hydrogen consumption and the parameters of reactor and purifier are deduced.…”

“…In the hydrogen purity profile, every horizontal section represents a sink or source. Every vertical section is a tie line connecting the two adjacent sources or sinks and is termed the source tie line or sink tie line . For example, in Fig.…”