Synthesis and Reactions of Selenothioic Acid <i>S</i>-Esters and Diselenoic Acid Esters

The development of chiral selenium catalysts for asymmetric transformations has become a pre‐eminent topic in the field of organocatalytic chemistry. Herein, we report the development of chiral bifunctional selenide catalysts bearing a hydroxy group and discuss their application to asymmetric bromolactonization reactions. The importance of the bifunctional design of chiral selenide catalysts for enantioselective bromolactonizations was clearly demonstrated in the present work.

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

Murai¹,

Morikawa²,

Maruyama³

2013

Chemistry A European J

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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.

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Synthesis and Reactions of Selenothioic Acid S-Esters and Diselenoic Acid Esters

Cited by 10 publications

References 16 publications

Selenocarbonyls

Selenocarbonyls

Chiral Bifunctional Selenide Catalysts for Asymmetric Bromolactonization

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

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