ChemInform Abstract: Steric Hindrance Facilitated Synthesis of Enynes and Their Intramolecular [4 + 2] Cycloaddition with Alkynes.

✍ Scribed by J. J. GONZALEZ; A. FRANCESCH; D. J. CARDENAS; A. M. ECHAVARREN

• Publisher: John Wiley and Sons
• Year: 2010
• Weight: 43 KB
• Volume: 29
• Category: Article
• ISSN: 0931-7597
• DOI: 10.1002/chin.199834127

✦ Synopsis

Steric Hindrance Facilitated Synthesis of Enynes and Their Intramolecular [4 + 2] Cycloaddition with Alkynes. -The unexpected formation of enediyne (IV) under Sonogashira-coupling conditions is explained by a regioselective Pd-catalyzed insertion reaction facilitated by steric hindrance resulting in an advantageous bending of the second alkyne out of linearity. The enediynes obtained by this [cf.(IV)] or other routes [cf.(X)] undergo type II [4 + 2] cycloadditions to furnish polycyclic aromates. A study on the steric hindrance facilitated direct synthesis of enediynes using bulky peri or ortho substituents is mentioned briefly; the configuration of compound (XVII), isolated as a single isomer, is not assigned. -(GONZALEZ,