2,5-Dihydro-2,2-dimethoxy-5,5-dimethyl-1,3,4-oxadiazole

CAS 138723-90-7, Cat. No EN300-6767469
Precursor of carbene for cyclization and homologation

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2,5-Dihydro-2,2-dimethoxy-5,5-dimethyl-1,3,4-oxadiazole is a bench-stable precursor of dimethoxycarbene, generating this highly nucleophilic carbene upon thermolysis or photolysis with extrusion of nitrogen and formation of acetone as the only by-product¹. It provides a convenient, scalable, and operationally simple alternative to diazirines for synthetic applications and can be stored for extended periods without detectable decomposition². The reagent has broad synthetic utility through the reactivity of the generated dimethoxycarbene. It enables [4+1] cycloadditions with vinyl isocyanates, electron-deficient dienes, and α,β-unsaturated carbonyl compounds to afford hydroindolones, pyrrolinones, cyclic orthoesters, dihydrofurans, spirodihydrofurans, and related O-heterocycles^3,4. It also participates in ring-expansion reactions of cyclic ketones and anhydrides, cyclopropanation, thiirane formation, hydantoin synthesis, orthoester formation, and carbonyl homologation via the intermediate dimethoxycarbene or carbonyl ylide. The methodology exhibits broad substrate scope, including vinyl isocyanates, ketones, cyclic anhydrides, 1,2-diones, cyclobutenediones, electron-deficient alkenes, and α,β-unsaturated aldehydes and ketones, with good tolerance toward esters, ethers, halides, heterocycles, and other functional groups. The reaction outcome is largely governed by the electrophile and reaction conditions, thereby allowing selective access to diverse heterocyclic frameworks.

Synonyms: 2,2-dimethoxy-5,5-dimethyl-Δ³-1,3,4-oxadiazoline; 2,2-dimethoxy-5,5-dimethyl-delta3-1,3,4-oxadiazoline