Formal Asymmetric Cycloaddition of Activated α,β-Unsaturated Ketones with α‑Diazomethylphosphonate Mediated by a Chiral Silver SPINOL Phosphate Catalyst
2019-01-11T19:19:46Z (GMT) by
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% <i>ee</i>, 99:1 <i>dr</i>) and yields (up to 95%). A stepwise mechanism is proposed based upon density functional M11 calculations.
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