Reaction of Thiols With Epoxides of Conjugated 1,4-Diketones

Abstract

The reaction of thiols with 2,3-epoxides of bicyclo, conjugated 1,4-diketones was found to proceed readily to give the dehydrated thio-substituted enediones or their enolized isomers, depending upon the reaction conditions and the bicyclic bridging of the starting materials. In no case was a mixture of these isomers observed. Enediones generally resulted from these reactions with and without triethylamine catalysis, whereas the use of an equimolar amount of triethylamine generally gave hydroquinones. The ease of rearrangement of enedione to hydroquinone followed the order: 2,3-dimethylbutadiene adduct [Formula: see text] reduced cyclopentadiene adduct > cyclopentadiene adduct = 1,3-cyclohexadiene adduct.

Influence of the Sulfinyl Group on the Chemoselectivity and π-Facial Selectivity of Diels−Alder Reactions of (S)-2-(p-Tolylsulfinyl)-1,4-benzoquinone

“…The endo configuration of 4a and 4b was confirmed as depicted in Scheme . The reaction of 2-( p -tolylthio)-1,4-benzoquinone (5) with cyclopentadiene yielded adduct 6 , whose controlled oxidation with m-CPBA afforded a 60:40 diastereoisomeric mixture of the corresponding racemic sulfoxides ( ±)- 4a and ( ±)- 4b , their 1 H-NMR spectra being identical to those obtained for optically pure compounds 4a and 4b . Therefore, both sulfoxides must exhibit the same endo or exo configuration because they derive from the same thioether.…”

“…endo -5,8-Methano-2-( p -tolylthio)-4a,5,8,8a-tetrahydro-1,4-naphthoquinone (6). A solution of 2-( p -tolylthio)-1,4-benzoquinone (5) 7 (100 mg, 0.34 mmol) and cyclopentadiene (100 μL, 1.5 mmol) in 5 mL of CH 2 Cl 2 was stirred at rt for 2 h. The solvent was evaporated in vacuo and the residue purified by crystallization in hexane to afford compound 6 (90% yield) as a yellow solid: mp 150−152 °C (lit …”

Dysprosium(III)‐Catalyzed Ring‐Opening of meso‐Epoxides: Desymmetrization by Remote Stereocontrol in a Thiolysis/Elimination Sequence

“…The usual substituent group of the meso ‐epoxide is either alkyl or aryl, for example, cis ‐cycloalkane or cis ‐stilbene. However, these approaches are limited when R=carbonyl group . The lack of related literature is most likely because of the lower reactivity of the oxirane ring on diketoepoxides compared with that of normal epoxides, and therefore the ring‐opening process of diketoepoxides requires harsh reaction conditions .…”

Synthesis, Antioxidant and Cytotoxic Activities of Novel Naphthoquinone Derivatives from 2,3-Dihydro-2,3-Epoxy-1,4- Naphthoquinone

“…The reactions with nucleophiles such as oxygen compounds [2][3][4][5][6], nitrogen compounds [7,8], thiols [9][10][11] and various carbon nucleophiles [12,13] were performed in both organic and aqueous solvents. The reactions with nucleophiles such as oxygen compounds [2][3][4][5][6], nitrogen compounds [7,8], thiols [9][10][11] and various carbon nucleophiles [12,13] were performed in both organic and aqueous solvents.…”