An expedient carbon-sulfur bond formation explored through the cellulose sulfonic acid (CSA) catalyzed dithioacetal protection of carbonyl compounds

摘要

A facile carbon-sulfur bond formation was observed through the cellulose sulfonic acid (CSA) catalyzed dithioacetal protection of carbonyl compounds. In a preliminary study, the synthesis and characterization of functionalized bio-polymer, cellulose sulphonic acid (CSA) was achieved and its catalytic knack for dithioacetal protection was studied. It was discovered that CSA is an efficient, environmentally benign, recyclable catalyst for the synthesis of 1,1-dithioacetals or 1,1-dithioketals. A diverse range of aldehydes or ketones smoothly underwent the thioacetalization either with 1,3-dithiol or 1,2-dithiol. The 1,3-dithiol protection was found favored over 1,2-dithiol in terms of yields and reaction times. Acetonitrile at room temperature provides the best results among the solvents studied. The biodegradable nature of CSA, operationally simple protocol, good to excellent yields, shorter reaction times and need of very small amount of catalyst are the salient features of the present protocol.