Synthesis of 4‐(Indol‐1‐yl)butanals via Rhodium‐Catalyzed Hydroformylation of 1‐Allylindoles

Abstract

The rhodium‐catalyzed hydroformylation of new 1‐(β‐methallyl) indoles 1a–e carried out with Rh₄ (CO)₁₂ as the catalyst precursor, at 100 atm total pressure and 100°C, produces the 4-(indol‐1‐yl)‐3‐methylbutanals 2a–e as the sole products in high yields. The synthesized 4‐indolylbutanals are stable under the adopted conditions and are isolated and characterized here for the first time. The preparation of the starting 1‐allylindoles is described too.

Keywords:

• allyl olefins
• butanals
• indoles
• rhodium‐catalyzed hydroformylation
• synthesis

Acknowledgments

Financial support by MIUR—Programma di Ricerca Scientifica di Rilevante Interesse Nazionale is gratefully acknowledged.