Phosphine-promoted [3+2] cyclizations of allenic esters or phosphonates with coumarin derivatives were used to synthesize functionalized bicyclo[4.3.0]chroman-2-ones. Analogous bicyclo[4.3.0]quinolinones were similarly prepared by a two-step strategy involving a phosphine-catalyzed [3+2] cyclization of diethyl propadienylphosphonate and 3-(2-nitrophenyl)acrylate as the key step. Enantiomerically enriched compounds, with enantiomeric excesses in the range 70-86%, were obtained by using (S,S)-FerroPHANE as the chiral catalyst for the cyclization step.
A catalytic asymmetric conjugate allylation was successfully developed to synthesize potential pharmacologically active 4-allyl-2-oxochroman skeletons. A dual activation strategy was employed by using N,N′-dioxide-Yb(OTf)3 to activate coumarins and using (CuOTf)2•C7H8 to activate tetraallyltin viatransmetalation, respectively. Good yields and enantioselectivities were obtained under mild conditions
催化不对称共轭烯丙基化已成功开发,以合成潜在的药理活性的4-烯丙基-2-氧代苯并二氢吡喃骨架。通过使用N,N'-二氧化物-Yb(OTf)3激活香豆素并使用(CuOTf)2 •C 7 H 8来通过跨金属化激活四烯丙基环丁胺,采用双重激活策略。在温和的条件下获得了良好的收率和对映选择性。