218. Nitrogeneous by-products in the Cadiot–Chodkiewicz reaction

Abstract

The cuprous-catalysed coupling reaction between l-bromoacetylenes and terminal acetylenes in the presence of primary amines has been shown to produce amidoxime and amidine by-products in certain circumstances.

Strained Dehydrobenzoannulenes

“…[52] It decomposed explosively when ground or when heated above 80°C. In its 1 H NMR spectrum, the aromatic protons of 45a resonate at 7.08-7.02 and 6.98-6.92 ppm, indicating a paratropic character.…”

Synthetic Strategies for Dehydrobenzo[n]annulenes

“…[19] Alkyne dimerization of the starting material by using Cu(OAc) 2 in pyridine allowed no possibility for the formation of cyclic materials (Scheme 7). Elimination on the bromo intermediate gave 19 which was intramolecularly homocoupled to form 1.…”

Macrocycles Based on Phenylacetylene Scaffolding

“…While the former technique can afford either monoyne-or diyne-linked products, this latter route has only been successfully used to prepare monoyne structures. 8.2.1.1 nX = Z The first example of a phenyldiacetylene macrocycle (PDM) reported in the literature was described by Eglinton and co-workers in the late 1950s [7]. The authors believed they had isolated the trimeric [18]annulene 1 after oxidatively coupling the terminal acetylene moieties of o-diethynylbenzene (2) through treatment with Cu(OAc) 2 in pyridine under high-dilution conditions (Scheme 8.1).…”

“…The authors believed they had isolated the trimeric [18]annulene 1 after oxidatively coupling the terminal acetylene moieties of o-diethynylbenzene (2) through treatment with Cu(OAc) 2 in pyridine under high-dilution conditions (Scheme 8.1). However, they subsequently reported that the reaction product was the strained dimeric [12]annulene 3, and no evidence to support the formation of higher macrocyclic analogues such as 1 was obtained [8]. Although cyclodimer 3 proved somewhat difficult to manipulate, the authors obtained a low-resolution X-ray structure of the compound that showed the "bowed" diacetylenic linkages, which in turn impart significant strain upon the molecule [9].…”

“…Our review surveys the main synthetic strategies employed to prepare phenyl-and acetylene-containing macrocycles, provides a synopsis of the compounds prepared to date, and also offers an overview of the properties and reactivity of these novel molecules. 8.2…”