π-Facial Diastereoselection in Diels−Alder Reactions of (R)-4-[(p-Tolylsulfinyl)methyl]quinols

Abstract

Diels−Alder reactions of a range of (R)-4-hydroxy-4-[(p-tolylsulfinyl)methyl]-2,5-cyclohexadienones with cyclopentadiene and 1,3-pentadiene proceed in a total π-facial diastereoselective manner from the C-4 OH side. Ab initio calculations at the RHF/6-31G* theory level provide data on transition-state energies for cycloadditions with cyclopentadiene in full agreement with the experimental results.

Asymmetric [4+2] Cycloadditions Mediated by Sulfoxides

“…This reaction was further extended to other sulfinylquinones and dienes with very similar stereochemical results. Ab initio calculations provide data on transition states energies for cycloadditions with cyclopentadienes in full agreement with the experimental results [174].…”

Gram-Scale Synthesis of the A′B′-Subunit of Angelmicin B

“…14 Additionally, the Cieplak model has been invoked to rationalize the stereochemical outcome for the aforementioned Diels–Alder reaction. 15 In accordance with this line of reasoning, formation of the β-C–C bond syn with the electron-withdrawing γ-OTBS group stabilizes the forming σ*-C–C orbital through hyperconjugation with the electron-donating σ-C–H bond (transition state 2, Scheme 3). It is plausible that a synergism of individually small stereoelectronic effects bias the reaction pathway towards the observed product diastereomer 11 .…”

Stereoselective Synthesis of Heterocyclic Cage Compounds by Domino Conjugate Additions

“…The absolute configuration of the stereogenic amino‐substituted carbons in diastereomers 8 could be assigned on the basis of a comparative analysis of their 1 H NMR parameters with those of [(S) R ]‐ 7 and the p ‐quinols [(S) R ]‐ 9 , [4 R ,(S) R ]‐ 10 as well as the 3,5‐dimethyl‐substituted analogue whose structure had been already assigned 6a, 7a. The most significant data correspond to the different chemical shifts observed for the substituents situated at the olefinic β ‐carbons (H and CH 3 ).…”