Electrophilic Amination of Carbanions, Enolates, and Their Surrogates

Abstract

This chapter deals with the formation of carbon‐nitrogen bonds by reaction of carbon nucleophiles with electrophilic aminating reagents. The former encompass aliphatic and aromatic carbanions, enolates and their surrogates such as enamines, enol esters, and enol ethers, as well as carbanions stabilized by cyano or sulfone groups or by phosphorus. A section entitled Reagents and Mechanisms lists the many aminating reagents available and discusses the mechanisms by which the more important ones react. Among the electrophiles discussed are halo amines, various hydroxylamine derivatives, oxaziridines, imines, oximes, diazonium salts, diazo compounds, azo compounds, and azides. The section on Scope and Limitations is organized by carbon nucleophiles and attempts to suggest the best reagents for each class. A number of electrophilic aminating reagents that have been omitted from the scope of this chapter are briefly discussed, with references to reviews, in the section on Comparison with Other Methods. Tables listing references to the preparation of the various aminating reagents are found in the section on Experimental Conditions. References to the conversion of non‐amine products into amines are also provided there. The literature is covered to the middle of 2007.

Non-Deprotonative Primary and Secondary Amination of (Hetero)Arylmetals

“…Although copper catalyzed/mediated aminations of arylmetals have been reported in the literature, 11 the vast majority can only produce tertiary amines due to the lack of suitable electrophilic “NH 2 ” equivalents. As mentioned earlier, the Uchiyama group recently reported a method in which an arylcuprate could be efficiently aminated using O -benzyl-hydroxylamine (BnONH 2 , Figure 1B).…”

Copper-Catalyzed Electrophilic Amination of sp2 and sp3 C−H Bonds

“…Electrophilic amination reactions have seen a considerable increase in interest over the past decade as an alternative method for the synthesis of ubiquitous C−N bonds. [35][36][37][38][39][40][41][42][43][44] The key to these amination reactions is the use of [NR 2 ] + synthons as the nitrogen source. Many electrophilic aminations have been achieved using various organometallic reagents, [45][46][47][48][49][50][51][52][53][54][55][56][57][58] while significant advances have also been achieved via C−H functionalization.…”

“…[36][37][38][39][40]134 Umpolung electrophilic aminations have received significant attention as an alternative and complementary strategy to traditional nucleophilic aminations for C-N bond formation. [35][36][37][38][39][40][41][42] Electrophilic amination of α-carbanions represents one of most general and important methods for the synthesis of α-amino carbonyl compounds. [38][39][40] Towards this, a variety of electrophilic nitrogen-transfer reagents have been developed for amination of enolates and eniminates ( Figure 5).…”

“…[35][36][37][38][39][40][41][42] Electrophilic amination of α-carbanions represents one of most general and important methods for the synthesis of α-amino carbonyl compounds. [38][39][40] Towards this, a variety of electrophilic nitrogen-transfer reagents have been developed for amination of enolates and eniminates ( Figure 5). Electrophilic aminating reagents used for the preparation of α-aminocarbonyl Figure 5.…”

Formal anti-Markovnikov Hydroamination of Terminal Aryl Alkynes with Pinacolborane and Hydroxylamines via Zr/Cu Sequential Catalysis

“…Meanwhile, our group 9 and others 10 have recently focused on the unique reactivity of chloramines and hydroxylamine derivatives and succeeded in the catalytic CN bond formation through an electrophilic amination. In this context, we envisioned that a combination of regioselective hydroboration of terminal alkynes and electrophilic amination of preformed alkenylborane intermediates could be a good alternative to the above hydroamination protocols.…”