Synthesis of unsaturated compounds
A palladium-catalyzed carbonylative transformation of organic halides with formic acid as the coupling partner provides carboxylic acids in the presence of a catalytic amount of DCC as the activator. Both vinyl and aryl (pseudo)halides were conveniently transformed into the corresponding acids in good yields.
F.-P. Wu, J.-B. Peng, X. Qi, X.-F. Wu, J. Org. Chem., 2017, 82, 9710-9714.
1-Siloxy-1-alkenylcopper species were generated by 1,2-Csp2-to-O silyl migration of the copper enolates of acyltriphenylsilanes. The alkenylcopper species reacted with methyl, benzyl, allylic, tributylstannyl halides and in the presence of Pd(0) catalyst with aryl and alkenyl iodides to give geometrically pure (Z)-enol silyl ethers.
A. Tsubouchi, K. Onishi, T. Takeda, J. Am. Chem. Soc., 2006, 128, 14268-14269.
A copper-promoted reaction of 1-alkynes with α-carbonyl aldehydes in the presence of morpholine enables an efficient and highly regio- and stereoselective synthesis of E-1,2-dicarbonyl-3-ene derivatives.
S. Chen, Y. Li, H. Zhao, B. Li, J. Org. Chem., 2014, 79, 4137-4141.
A 1,4-dipolar intermediate generated from pyridine and dimethyl acetylenedicarboxylate reacted with aldehydes to give 2-benzoylfumarates via the elimination of pyridine, whereas with N-tosylimines as dipolarophiles the reaction afforded highly substituted 1-azadienes.
V. Nair, A. R. Sreekanth, N. Abhilash, A. T. Biju, B. R. Devi, R. S. Menon, N. P. Rath, R. Srinivas, Synthesis, 2003, 1895-1902.
The Rh(I)-catalyzed [3 + 2] cycloaddition of cyclopropenones and alkynes provides a highly efficient and regioselective route to cyclopentadienones (CPDs) that would be otherwise difficult to obtain. The versatility of the method is explored with a wide range of alkynes and diaryl- as well as arylalkylcyclopropenones.
P. A. Wender, T. J. Paxton, T. J. Williams, J. Am. Chem. Soc., 2006, 128, 14814-14815.