Synthesis of Functionalized Aryloxy 1,3-Butadienes and Their Transformation to Diaryl Ethers via Diels-Alder Cycloaddition Reactions

• Published in: Journal of organic chemistry Vol. 60; no. 19; pp. 6025 - 6031
• Main Authors: Olsen, Richard K, Feng, Xianqi, Campbell, Magnus, Shao, Rui-lian, Math, Shivanand K
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 01.09.1995; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Organic; Physical Sciences; Science & Technology; PENALDIC ACID EQUIVALENT; K-13; I CONVERTING ENZYME; OF4949-III; DEOXYBOUVARDIN; TUMOR CYCLIC HEXAPEPTIDES; DERIVATIVES; AMINOPEPTIDASE-B; MACROCYCLIZATION; RA-VII
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo00124a010

The Diels-Alder reaction involving cycloaddition of aryloxy-substituted 1,3-butadienes with appropriate acetylenic electrophiles, followed by aromatization of the newly formed cyclohexadiene ring, has been used for the synthesis of diaryl ethers. The functionalized aryloxy 1,3-butadienes employed in this study were prepared by either of two methods: (1) methylenation of aryl esters via the Tebbe or related reagents, and (2) from 1-(aryloxy)-2-propanone by a sequence of formylation or alkylthio methlylenation, and subsequent enolsilylation. A tetrasubstituted butadiene containing two phenoxy groups at the 1 and 3 positions also was prepared by the latter method. The cycloaddition reactions of 2,3-dioxy-substituted dienes occurred in high yield, but, as expected, with no regioselectivity to furnish nearly equal mixtures of regioisomeric cycloadducts. In contrast, application of 1,2,3-trihetero-substituted dienes resulted in regiospecific cycloaddition reactions. Transformation of the cyclohexadiene cycloadducts to an aromatic ring was accomplished by dehydrogenation with DDQ or by elimination during the cycloaddition process of a molecule of an alkyl mercaptan. A chiral acetylenic ketone derived from D- or L-serine underwent condensation, without racemization, with aryloxy dienes to provide diaryl ethers related to the isodityrosine antibiotics.