Synthesis with Perfect Atom Economy: Generation of Furan Derivatives by 1,3-Dipolar Cycloaddition of Acetylenedicarboxylates at Cyclooctynes

Abstract

Cyclooctyne and cycloocten-5-yne undergo, at room temperature, a 1,3-dipolar cycloaddition with dialkyl acetylenedicarboxylates 1a,b to generate furan-derived short-lived intermediates 2, which can be trapped by two additional equivalents of 1a,b or alternatively by methanol, phenol, water or aldehydes to yield polycyclic products 3b-d, orthoesters 4a-c, ketones 5 or epoxides 6a,b, respectively. Treatment of bis(trimethylsilyl) acetylenedicarboxylate (1c) with cyclooctyne leads to the ketone 7 via retro-Brook rearrangement of the dipolar intermediate 2c. In all cases, the products are formed with perfect atom economy.

Functionalized 1,3-Thiazolidin-4-Ones from 2-Oxo-Acenaphthoquinylidene- and [2.2]Paracyclophanylidene-Thiosemicarbazones

“…A literature survey revealed that, the tetramerization reaction is one of the most fascinating reactions of both dialkyl acetylenedicarboxylic acid derivatives occurring at 25 °C for several days or by heating it alone or in solution for several hours [51,52,53]. Furthermore, trimer [54] and dimer [55] forms were reported for compound 6a . Recently, Huang et al [56] have reported the reaction of 2,2′-bis(azaphosphindole) with four equivalents of 6a in THF at room temperature to afford a tetramer complex of 6a with 2,2′-bis(azaphosphindole).…”