SYNTHESIS OF SUBSTITUTED INDENE COMPOUNDS
Publication Date: 2004-Aug-05
The IP.com Prior Art Database
Functionalized indenes, such as 2-methyl-4-phenylindene, are prepared from substituted phenols (E=O), anilines (E=NH), or allylic halides (or pseudohalides) in a simple, high yield process entailing four primary steps as shown in Scheme 1. The four steps are: (1) Formation of an allylic ether or amine through alkylation of a phenol or aniline (illustrated) or by coupling of an aryl halide with an allylic alcohol or amine (not illustrated). (2) Claisen rearrangement of the allylic aryl ether or amine. (3) Conversion of the phenol or amine group to a suitable halide, sulfonate, phosphate, or diazonium cation leaving group (X). (4) Intramolecular coupling to form the indene ring via either: (a) Heck coupling of the resultant Ar-X with the olefinic C H bond; or (b) 1) Olefin cross-metathesis of the olefin with a vinyl boronic acid or ester, and 2) Suzuki coupling of the resulting vinyl boronic acid or ester with Ar-X. (The boronic acid may be converted to a boronic ester prior to the coupling, if desired).