A Formal [3+2] Annulation of
<i>β</i>
‐Oxoamides and 3‐Alkyl‐ or 3‐Aryl‐Substituted Prop‐2‐Ynyl Sulfonium Salts: Substrate‐Controlled Chemoselective Synthesis of Substituted
<i>γ</i>
‐Lactams and Furans
A substrate‐controlled synthesis of substituted γ‐lactams and furans has been developed via a formal [3+2] annulation of β‐oxoamides and 3‐alkyl/arylprop‐2‐ynyl sulfonium salts in the presence of cesium carbonate in a chemoselective manner. This novel protocol features easily available starting materials, mild reaction conditions, simple execution, and good to excellent yields of products.
Synthesis and transition metal catalysed reactions of 1-Ureido-3-propargyl-2,3-dihydropyrrol-2-ols, 1-ureido-3-propargylpyrroles and 1-ureido-3-propargyl-3-phosphono-1H-pyrrol-2(3H)-ones
作者:Antonio Arcadi、Orazio A Attanasi、Lucia De Crescentini、Elisabetta Rossi、Franco Serra-Zanetti
DOI:10.1016/s0040-4020(96)00064-6
日期:1996.3
The title compounds were obtained by reaction of conjugated azoalkenes with activated methinic derivatives bearing a propargylic residue. 1-Ureido-3-propargyl-2,3-dihydropyrrol-2-ols gave in the presence of Cu(I) catalyst the 2,5-dimethyl-3-ethoxycarbonyl-4-(2-oxopropyl)-1-(N'-phenylureido)-pyrrole. while in the presence of Pd(0) or An(3+) the 3,6-dimethyl-5-ethoxycarbonyl-4-propargyl-1,4-dihydropyridazine was obtained by ring opening and ring expansion reaction. The propargylic side chain of 1-ureido-3-propargylpyrroles and 1-ureido-3-propargyl-3-phosphono-1H-pyrrol-2(3H)-ones was functionalised by means of palladium and/or copper catalysed coupling reactions with aryl or vinyl triflates and halides.