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Prins reaction in the synthesis of lignin model compounds. III. Alternative synthesis of pinoresinol, coniferyl aldehyde, and guaiacyl vinyl ketone

R. Brežný and J. Alföldi

Institute of Chemistry, Slovak Academy of Sciences, 842 38 Bratislava

 

Abstract: A possibility to convert 4-aryl-5-bromo-1,3-dioxanes, which are the products of Prins reaction on β-bromostyrenes, to the mixt. of corresponding (E)-3-aryl-2-propen-1-ols and 1-aryl-2-propen-1-ols was demonstrated. This conversion, effected by Zn in wet DMF, allowed the prepn. of hitherto unknown 4-O-acetylconiferyl alc. and 4-O-acetylguaiacylallyl alc., as well as their 5-bromo analogs, in the ratio about 5:1 and total yield over 85%. All four alcs. were oxidized to the corresponding carbonyl compds. subsequently deacetylated to give phenolic cinnamaldehydes and aryl vinyl ketones. Coniferyl and 5-bromoconiferyl alcs. obtained by deacetylation of their 4-O-acetates were oxidatively coupled to the corresponding resinols in yields of 40 and 58%, resp. Although, debromination of 5,5'-dibromopinoresinol by catalytic hydrogenolysis of C-Br bonds gave high yields, application of bromine atom as a protective group in position 5 on the arom. ring of coniferyl alc. offered, therefore, little advantage. Mass spectral characteristics and 1H-NMR data of the compds. prepd. are given.

Full paper in Portable Document Format: 362a267.pdf

 

Chemical Papers 36 (2) 267–276 (1982)

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