Sequential One‐Pot Addition of Excess Aryl‐Grignard Reagents and Electrophiles to O‐Alkyl Thioformates

Abstract

The sequential addition of aromatic Grignard reagents to O-alkyl thioformates proceeded to completion within 30 s to give aryl benzylic sulfanes in good yields. This reaction may begin with the nucleophilic attack of the Grignard reagent onto the carbon atom of the O-alkyl thioformates, followed by the elimination of ROMgBr to generate aromatic thioaldehydes, which then react with a second molecule of the Grignard reagent at the sulfur atom to form arylsulfanyl benzylic Grignard reagents. To confirm the generation of aromatic thioaldehydes, the reaction between O-alkyl thioformates and phenyl Grignard reagent was carried out in the presence of cyclopentadiene. As a result, hetero-Diels-Alder adducts of the thioaldehyde and the diene were formed. The treatment of a mixture of the thioformate and phenyl Grignard reagent with iodine gave 1,2-bis(phenylsulfanyl)-1,2-diphenyl ethane as a product, which indicated the formation of arylsulfanyl benzylic Grignard reagents in the reaction mixture. When electrophiles were added to the Grignard reagents that were generated in situ, four-component coupling products, that is, O-alkyl thioformates, two molecules of Grignard reagents, and electrophiles, were obtained in moderate-to-good yields. The use of silyl chloride or allylic bromides gave the adducts within 5 min, whereas the reaction with benzylic halides required more than 30 min. The addition to carbonyl compounds was complete within 1 min and the use of lithium bromide as an additive enhanced the yields of the four-component coupling products. Finally, oxiranes and imines also participated in the coupling reaction.

Chemistry of Ketene N,S-Acetals: An Overview

“…This reaction presents an alternative approach for the synthesis of 2,3-dicarbonylpyrrole derivatives. , In contrast with the construction of 88 , in the synthesis of 95 with N -methylprop-2-yn-1-amine as the amine component, the thiophilic nucleophilic reaction ,− for formation of thiiranium intermediate 98 , (also see Scheme ) should be critical for the formation of 95 via 1,2-acyl migration (Scheme ). …”

Reaction of Selenoamide Dianions with Thio- and Selenoformamides Leading to the Formation of 5-Aminoselenazoles: Photophysical and Electrochemical Properties

“…However, with these methods, amino groups cannot be introduced at the 5-positions of selenazoles. Very recently, sulfur isologues of 5- N , N -diarylaminoselenazoles were prepared for the first time in our studies on chalcogenocarbonyl and chalcogenophosphoryl compounds . In this reaction, thioamide dianions were generated from secondary thioamides and treated with thioformamides (Scheme ).…”

Kinetic Resolution of Secondary 2‐Aryl‐1‐cycloalkanols with Phosphoroselenoyl Chloride with a Binaphthyl Group

“…We recently developed phosphoroselenoic acid derivatives bearing a 1,1′‐binaphthyloxy group as new chiral molecular tools in our studies on organochalcogen compounds . The starting chlorides 1 are readily prepared by reacting PCl 3 with binaphthol and elemental selenium in the presence of a base (Scheme ).…”