Quantitative studies in stereochemistry. B. Photochemistry. III. Ratios of diastereomeric pinacols formed in the ultraviolet-promoted bimolecular reduction of selected para-substituted acetophenones

Configuration of the Major Stereoisomer of Zn/AcOH Reduction Product of 4-oxo-4H-chromene-3-carbaldehyde

“…[1][2][3][4][5][6][7][8] Aromatic aldehydes are known to undergo bimolecular reductive coupling yielding pinacols under a variety of reducing condition. [9][10][11][12][13] In connection with our study of the reaction of different oxygen heterocycles having unsaturated carbonyl moiety, in modified Clemmensen reduction condition, we have considered 4-oxo-4H-chromene-3-carbaldehyde as easily available starting material. Concurrent to this work, Bandyopadhyay et al 14 reported the formation of only one 1,2-diol compound from 4-oxo-4H-chromene-3-carbaldehyde in modified Clemmensen reduction condition and they did not mention the configuration of their reported compound.…”

Aluminium-mediated Reductive Dimerization of Aromatic Dialdehydes

“…The ratios of (±)-and meso-isomers of 2a-d were determined by IH NMR. 6 The coupling reactions of the 1,4-dialdehydes la and Id showed a high (±)-selectivity. However, this was not the case for the 1,3-dialdehydes Ib,c, One possible explanation for this difference can be the presence of the carbonyl group in the 4-position of the 1,4-dialdehydes.…”

Quantitative studies in stereochemistry. 16. The ratio of diastereomeric pinacols produced in the aluminum amalgam bimolecular reduction of acetophenone

“…Yields and diastereomeric ratios were determined by NMR. 15 The preformed aluminum alkoxide studies differed only in the replacement of the components of aluminum amalgam with the preformed reagent; e.g., 4.1 g of freshly distilled aluminum 2propoxide,16 0.122 g of acetophenone, 10 mL of 2-propanol, and 10 mL of benzene refluxed 4 h produced a nearly quantitative yield of methylphenylcarbinol and no pinacol.…”