Evidence for the Intermediate Occurrence of Acetylenedicarboxyimide

Abstract

We formulate scission of the carbon-mercury bond by iodine as an SEi process, depicted in (3) [41. Since this should proceed also with other reagents, it should be possible to prepare further hetero-substituted diazoacetic esters from the compound ( I ) 151. Photolysis of (2) (450 W Hanovia lamp, Pyrex filter) gave ethoxycarbonyliodocarbene (4), from which we obtained ethyl l-iodo-2,2-dimethylcyclopropanecarboxylate (5) (b.p. 45 "CiO.4 mm; yield 40%; NMR signals of the cyclopropane protons as an AB spectrum at T = 8.7 with JAB w 6 Hz) on irradiation of (2) in isobutene until evolution of nitrogen ceased. Products formed by insertion in the C-H bond were not detectedr61. We conclude that the carbene (4) is more selective than ethoxycarbonylcarbene.

Understanding and Modulating Indolyne Regioselectivities

“…3 However, a compelling review by Reinecke casts doubt on the existence of this species. 2a Many other proposed hetarynes, such as didehydromaleimide, 5 didehydromaleic anhydride, 2a,6 imidazolyne, 7 coumaryne, 8 isoquinolynes, 9 and naphthyridynes 10 have also been called into question (Figure 1). 2a Nonetheless, a number of hetarynes are thought to be accessible, including indolynes, 11 quinolynes, 2a,12 pyrimidynes, 2a, 13 2,3-thiophyne, 2a,14 4,5pyridazyne, 15 and pyridynes.…”

Chapter 11. Heterocyclic chemistry

“…imide in the thermal decomposition of 1,4dithiintetracarboxydi-imides (41) comes from the isolation of the mellitriimide (42) in good yield 72. In contrast, attempts to trap acetylenedicarboxylic acid anhydride have been unsuccessful 73.…”