The synthesis of 3-aryl-3-azetidinyl acetic acid esters by rhodium(I)-catalysed conjugate addition of organoboron reagents

A practical route to 3-aryl-3-azetidinyl acetic acid esters is developed. The key step involves the rhodium(I)-catalysed conjugate addition of an organoboron reagent to an α,β-unsaturated alkene. Elaboration of one conjugate addition product to give a novel spiroazetidine ring system is also described.