A novel synthesis of flav-3-enes by claisen rearrangement

✍ Scribed by Rajaram Sankara Subramanian; Kalpattu Kuppusamy Balasubramanian

• Publisher: Elsevier Science
• Year: 1988
• Tongue: French
• Weight: 163 KB
• Volume: 29
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)82458-2

✦ Synopsis

I-Arylprop-2-ynyl aryl ethers (6) undergo a facile Claisen rearrangement in N,N-diethylaniline/o-dichlorobenzene to give flav-3-enes in good yields. Though the aryl propargyl ether Claisen rearrangement has been recognised as one of the simple routes for the synthesis of 2H-I-benzopyrans' there are hardly any reports about its application for the synthesis of flav-3-enes. Among the aryl substituted aryl propargyl ethers only the rearrangement -f a Few 3-phenylprop-2-ynyl aryl ethers (1) to the respective 2H-I-benzopyrans is known2. The rearrangement of but-3-yn-2-yl aryl ethers (2) and 2-methylbut-3-yn-2-yl aryl ethers (z), particularly the latter, proceed with great facility furnishing the corresponding benzopyrans'. In the light of these reports one could expect that I-arylprop-2-ynyl aryl ethers (6) should rearrange readily to the flav-3-enes. Further, the development of conjugation in the transition state in these cases should provide additional driving force for the initial 3,3-sigmatropic rearrange-4 ment . Surprisingly there are no reports in the literature even about the preparation of I-arylprop-2-ynyl aryl ethers.