Isoquinoline synthesis by C-H activation/annulation using vinyl acetate as an acetylene equivalent

Abstract

Vinyl acetate is used as an acetylene equivalent in rhodium(III)-catalysed C-H activation/annulation with aryl ketoxime esters. Extension to an aldoxime ester allows for a concise formal synthesis of decumbenine B.

Cp*M-Catalyzed Direct Annulation with Terminal Alkynes and Their Surrogates for the Construction of Multi-Ring Systems

“…Yu and Cheng (2015) 26 and Marsden (2018) 27 independently developed the Cp*Rh-catalyzed annulation of O-acetyl oximes with vinyl acetates (Scheme 16). This method afforded to produce various pyridines and isoquinolines in single operation and could be utilized for the concise preparation of papaverine: a well-established opium alkaloid antispasmodic drug.…”

Comprehensive Strategies for the Synthesis of Isoquinolines: Progress Since 2008

“…The methods holds good for wide range of substrates by giving good yields (Scheme 214). [226] Wu et al coined a Rh-catalyzed annulation reaction between ethyl benzimidates 86 and α-aroyl sulfur ylides 363 leading to the formation of pyrano [4,3,2-ij] isoquinoline derivatives 364 in moderate yields. Using the developed reaction conditions wide range of isoquinoline derivatives were synthesized with good functional group tolerance (Scheme 215).…”

Variability of Rhodium(III)-Catalyzed Reactions of Aromatic Oximes with Alkenes

“…Several groups have shown that reactions of O-acetyl oximes with dienes, 15 vinyl acetates, 16,17 vinyl aldehydes, 18 or ketones, 18 are accompanied by aromatization and give isoquinolines. Similar reactions proceed without aromatization in the case of activated alkenes such as ketenes 19 or urea-derived bicycle olefins.…”

“…A similar process has been observed previously for vinyl acetates. 16,17 The reaction of 1 with ethyl acrylate in MeCN resulted in Michael addition of the hydroxy group of the oxime to the activated double bond, giving product 4 in 89% yield. Interestingly, a similar reaction in DCE as solvent gave the disubstituted dihydroisoquinoline 5 in 65% yield (double substitution occurred even when only one equivalent of ethyl acrylate was used).…”