ChemInform Abstract: Asymmetric Reactions of 2-Methoxy-1,4-benzoquinones with Styrenyl Systems: Enantioselective Syntheses of 8-Aryl-3-methoxybicyclo[4.2.0]oct-3-en-2,5-diones, 7-Aryl-3-hydroxybicyclo[3.2.1]oct-3-en-2,8-diones, 2-Aryl-6-methoxy-2,3-dihydrobenzofuran-5-ols, and Pterocarpans.

✍ Scribed by Thomas A. Engler; Michael A. Letavic; Rajesh Iyengar; Kenneth O. LaTessa; Jayachandra P. Reddy

• Publisher: John Wiley and Sons
• Year: 2010
• Weight: 44 KB
• Volume: 30
• Category: Article
• ISSN: 0931-7597
• DOI: 10.1002/chin.199934029

✦ Synopsis

The chiral titanium complex, derived from TiCl 4 , Ti(O-iPr) 4 , and dioxole (+)-PPD, effectively promotes the enantioselective formation of compounds (III)/(VII) and (V)/(IX) in good yields and high e.e. from (E)-alkene (II) and benzoquinones (I) or (VI). Compounds (IV)/(VIII), which are also formed in these reactions, are obtained also from enantiomerically pure cyclobutanes (III)/(VII) by thermal rearrangement. (Z)-Alkene (X) or indene (XII) afford products in moderate enantiomeric purity. From anisylcycloalkenes (XVI) or (XIX) and benzoquinone (I) products with different absolute stereochemistry are formed depending on the ring size. An application of these reactions is demonstrated with the synthesis of some pterocarpan derivatives.

-(ENGLER, THOMAS A.;