ABSTRACT
In this paper, we report efficient cyanation of various peptides containing the α-bromocarbonyl moiety using a Cu-catalyzed radical-based methodology employing zinc cyanide as the cyanide source. Mechanistic studies revealed that in situ formed CuCN was a key intermediate during the catalytic cycle. Our method could be useful for the synthesis of modified peptides containing quaternary carbons.
ABSTRACT
There are several reports on the synthesis of alkylamines, but most of the reported methods are not suitable for the synthesis of hindered amines. In this research, we found that a copper catalyst is effective for the formation of congested C-N bonds at room temperature. Control experiments revealed that a copper amide is a key intermediate. Moreover, when a chiral amine was used, a quaternary carbon stereogenic center was created with good selectivity.
ABSTRACT
A copper-catalyzed site-selective fluorination of α-bromoamides possessing multiple reaction sites, such as primary and secondary alkyl-Br bonds, using inexpensive CsF is reported. Tertiary alkyl-F bonds, which are very difficult to synthesize, can be formed by this fluorination reaction with the aid of an amide group. Control experiments revealed that in situ generated CuF2 is a key fluorinating reagent that reacts with the tertiary alkyl radicals generated by the reaction between an α-bromocarbonyl compound and a copper(I) salt.