Formal Asymmetric Cycloaddition of Activated α,β-Unsaturated Ketones with α‑Diazomethylphosphonate Mediated by a Chiral Silver SPINOL Phosphate Catalyst

An efficient method for preparing highly functionalized chiral nonspiro-phosphonyl­pyrazolines via an asymmetric formal 1,3-dipolar cycloaddition reaction of α-diazomethyl­phosphonate with activated, acyclic α,β-unsaturated ketones, bearing an additional nitrile electron-withdrawing group, has been developed, utilizing an in situ generated chiral silver phosphate catalyst, affording excellent stereoselectivities (up to 98% ee, 99:1 dr) and yields (up to 95%). A stepwise mechanism is proposed based upon density functional M11 calculations.