Efficient One‐Pot Multifunctionalization of Alkynes en Route to α‐Alkoxyketones, α‐Thioketones, and α‐Thio Thioketals by using an Umpolung Strategy

Abstract The use of polarized synthons is a highly desirable strategy, as it generally enables unprecedented retrosynthetic disconnections for the synthesis of unique substances. Herein, a new approach for α‐oxygenated ketones, α‐thioketones and α‐thio thioketals via an intermolecular umpolung reaction between nucleophiles (alcohols/thioalcohols) and N ‐alkenoxypyridinium salts, which were generated from the corresponding alkynes, has been developed for the first time. The reactions proceed with good substrate scope and excellent functional group tolerance in one‐pot manner. Applications of the products, α‐oxygenated ketones, to the synthesis of other valuable synthetic moieties has also been successfully achieved.