Simple and Advantageneous Stereoselective Synthesis of (Z)-Allyl Phosphonates Starting from Baylis–Hillman Adducts

Abstract

Baylis–Hillman adducts 3-hydroxyl-2-methylene alkanoates have been converted in one pot into the corresponding (Z)-allyl phosphonates by treatment with FeCl₃ and trialkyl phosphites in toluene under reflux. The products are formed in excellent yields (88–98%) within 1–1.5 h. The process is highly convenient and efficient, cost-effective, and remarkably stereoselective.

GRAPHICAL ABSTRACT

Keywords:

• Arbuzov reaction
• Baylis–Hillman adduct
• FeCl₃
• trialkyl phosphite
• (Z)-allyl phosphonates

ACKNOWLEDGMENT

The authors thank the Council of Scientific and Industrial Research, New Delhi, for financial assistance.

Notes

^a Reaction conditions: Baylis–Hillman adduct, 1a (1 mmol), triethyl phosphite (1.2 mmol), Lewis acid (0.35 mmol), and toluene (10 ml) under reflux.

^b Yields of isolated pure compound after column chromatography.

^a Reaction conditions: Baylis–Hillman adduct, 1a (1 mmol), trialkyl/triphenyl phosphite (1.2 mmol), FeCl₃ (0.35 mmol), and toluene (10 ml); the reaction mixture was stirred for 1 h under reflux.

^b Yields of isolated pure compound after column chromatography.

^a Reaction conditions: Baylis–Hillman adduct, 1 (1 mmol), triethyl phosphate (1.2 mmol), FeCl₃ (0.35 mmol), and toluene (10 ml); the reaction mixture was stirred under reflux.

^b R¹ = Me and R^II = Et in each entity otherwise stated.

^c The products were characterized from their IR, ¹H NMR, ¹³C NMR, and HRMS spectra.

^d Yields of isolated pure compound after column chromatography.

Part 204 in the series, “Studies on novel synthetic methodologies.”