PPh<sub>3</sub>-KOBu<sup>t</sup>–Mediated Cyclization Reaction of <font>β</font>-Ketoesters with Alkynyl Ketones: Synthesis of Functionalized 2-Pyrones
Abstract Cyclization of alkynyl ketones with β-ketoesters mediated by PPh3 and KOBut to synthesize 2-pyrone derivatives was systematically described. A variety of β-ketoesters reacted with alkynyl ketones to give functionalized 2-pyrones in moderate to good yields under mild conditions.
Cycloaddition of Alkynyl Ketones with <i>N</i>-Tosylimines Catalyzed by Bu<sub>3</sub>P and DMAP: Synthesis of Highly Functionalized Pyrrolidines and Azetidines
Cycloadditions of alkynyl ketones with N-tosylimines catalyzed by Lewis bases to synthesize azetidines and pyrrolidines were systematically described. In the reaction of alkynyl ketones with N-tosylimines catalyzed by Bu3P at room temperature in toluene, highly functionalized pyrrolidines were formed in good to excellent yields. When DMAP was used in place of Bu3P as catalyst to facilitate the cycloaddition, completely substituted azetidines were produced in moderate to good yields in CH2Cl2. Both cyclization reactions proceeded smoothly with complete stereoselectivity. The scope and limitations of these cycloadditon reactions were also investigated.
SHENG HUAIYU; LIN SHOUYUAN; HUANG YAOZENG, TETRAHEDRON LETT., 27,(1986) N 40, 4893-4894