A general and regioselective synthesis of substituted pyrroles 2 by cycloisomerization of readily available (Z)-(2-en-4-ynyl)amines 1 is reported. Spontaneous cycloisomerization leading to 2 occurred in the course of preparation of enynamines bearing a terminal triple bond or a triple bond substituted with a phenyl or a CH2OTHP group. When the triple bond was substituted with an alkyl or alkenyl group
All‐Carbon [3+3] Oxidative Annulations of 1,3‐Enynes by Rhodium(III)‐Catalyzed CH Functionalization and 1,4‐Migration
作者:David J. Burns、Daniel Best、Martin D. Wieczysty、Hon Wai Lam
DOI:10.1002/anie.201503978
日期:2015.8.17
1,3‐Enynes containing allylic hydrogens cis to the alkyne function as three‐carbon components in rhodium(III)‐catalyzed, all‐carbon [3+3] oxidativeannulations to produce spirodialins. The proposed mechanism of these reactions involves the alkenyl‐to‐allyl 1,4‐rhodium(III) migration.
Versatile Synthesis of Pyrrole-2-acetic Esters and (Pyridine-2-one)-3-acetic Amides by Palladium-Catalyzed, Carbon Dioxide-Promoted Oxidative Carbonylation of (Z)-(2-En-4-ynyl)amines
The oxidative carbonylation of readily available (Z)-(2-en-4-ynyl)amines, catalyzed by the PdI2-KI system, selectively afforded in satisfactory yields (40–95 %) either pyrrole-2-acetic ester or (pyridine-2-one)-3-acetic amide derivatives, depending on the susbtitution pattern of the substrate and the reaction conditions. The presence of an excess of carbon dioxide proved in most cases to be beneficial
A general and facile synthesis of furans, based on Pd(II)-catalyzed cycloisomerization of (Z)-2-en-4-yn-1-ols, is described. Cycloisomerization reactions are carried out at 25-100 degrees C in the presence of a very simple catalytic system, consisting of K2PdI4, under essentially neutral conditions. This new methodology is very versatile and can be applied to the synthesis of a variety of substituted furans, including particularly fragile, naturally occurring furans such as rosefuran. Efficient synthetic approaches for the regioselective synthesis of suitably substituted (Z)-2-en-4-yn-1-ols have been developed.