Categories: C-N Bond Formation >
Synthesis of enamines
By employing Pd(OAc)2 and (t-Bu)2PNP(i-BuNCH2CH2)3N as ligand, a broad range of aryl bromides and chlorides possessing base-sensitive substituents provide coupling products with bulky aryl amines in good to excellent yields. An efficient coupling of vinyl bromides with a variety of amines produces imines and enamines at room temperature.
Ch. V. Reddy, J. V. Kingston, J. G. Verkade, J. Org. Chem., 2008, 73, 3047-3062.
Michael adducts are provided by a reaction of alkylidene malonates with enamines, which are generated from vinyl bromides and pyrrolidine by a prior palladium-catalysed C-N bond formation.
M. C. Willis, J. Chauhan, W. G. Whittinham, Org. Biomol. Chem., 2005, 3, 3094-3095.
A range of enol triflates can be coupled with amides, carbamates, and sulfonamides using palladium catalysis. This method allows the synthesis of enamides, which may not be readily available by other means.
D. J. Wallace, D. J. Klauber, C.-Y. Chen, R. P. Volante, Org. Lett., 2003, 5, 4749-4752.
Orangoselenium catalysis enables an efficient route to 3-amino allylic alcohols in excellent regio- and stereoselectivity in the presence of a base. In the absence of bases α,β-unsaturated aldehydes were formed in excellent yield. The hydroxy group is crucial for the direct amination.
Z. Deng, J. Wei, L. Liao, H. Huang, X. Zhao, Org. Lett., 2015, 17, 1834-1837.
Nucleophilic addition of sulfonamides to 1-bromo-1-alkynes provided (Z)-N-(1-bromo-1-alken-2-yl)-p-toluenesulfonamides in good yield and in a highly regio- and stereoselective manner. A subsequent reaction in the presence of a palladium catalyst under Heck conditions afforded substituted pyrroles in good yield.
M. Yamagishi, K. Nishigai, T. Hata, H. Urabe, Org. Lett., 2011, 13, 4873-4875.
An efficient intermolecular trans-selective β-hydroamidation of ynamides provides (Z)-ethene-1,2-diamide derivatives with excellent regio- and stereo-selectivities for a wide range of substrates. The reaction proceeds under basic conditions in the absence of a transition-metal catalyst.
Z. Peng, Z. Zhang, Y. Tu, X. Zeng, J. Zhao, Org. Lett., 2018, 20, 5688-5691.
Rhodium(II) azavinyl carbenes, which are conveniently generated from 1-sulfonyl-1,2,3-triazoles, undergo a facile, mild, and convergent formal 1,3-insertion into N-H and O-H bonds of primary and secondary amides, various alcohols, and carboxylic acids to afford a wide range of vicinally bisfunctionalized (Z)-olefins with perfect regio- and stereoselectivity.
S. Chuprakov, B. T. Worrell, N. Selander, R. K. Sit, V. V. Fokin, J. Am. Chem. Soc., 2014, 136, 195-202.