Direct Synthesis of [gamma]-Keto Sulfones from Allylic Alcohols: One-Pot Palladium(II)-Catalyzed Generation of Enones Followed by Water-Mediated 1,4-Addition of Organosulfinates

• Published in: European journal of organic chemistry 2016-07, Vol.2016 (21), p.3575
• Main Authors: Vellakkaran, Mari, Andappan, Murugaiah M S, Nagaiah, Kommu, Nanubolu, Jagadeesh Babu
• Format: Article
• Language: English
• Subjects: Alcohol
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201600494

Allylic alcohols were exploited as synthetic precursors of [gamma]-keto sulfones. The reaction involved the one-pot generation of [alpha],[beta]-enones in situ from the allylic alcohols by using a PdII-dioxygen catalytic system and subsequent sulfa-Michael addition in the presence of water. Importantly, water was identified as a sustainable substitute for a toxic copper salt to promote organosulfonyl addition. Diverse examples of aromatic and aliphatic [gamma]-keto sulfones were prepared. Specially, Ar-X (X = Br, Cl) bonds were tolerated, which indicated a chemoselective catalytic system for the preparation of halogen-bearing [gamma]-keto sulfones. This one-pot method does not require an acid, a base, or isolation of any intermediate. Control experiments indicated that the active catalyst of the first step also promoted the subsequent C-S bond-formation reaction. Water was found to accelerate the reaction rate and to be involved in the protonolysis of the σ-alkylpalladium complex, as corroborated by deuterium incorporation.