Ketone-derived 2,3-dihydroquinazolinones in <i>N</i>-heteroarene C–H alkylation <i>via</i> C–C bond scission under oxidative metal catalysis
作者:Pinku Prasad Mondal、Amit Pal、Athira K Prakash、Basudev Sahoo
DOI:10.1039/d2cc04947c
日期:——
activation of pre-aromatic 2,3-dihydroquinazolinone to generate an alkyl radical, supported by mechanistic studies. In addition to the broad scope, good functionality tolerance, late stage functionalization of APIs, and synthesis of a novel Papaverine analogue, the utilization of an N-heteroarene C–H bond and ketone as a non-trivial alkyl radical source represents the salient feature of this method.
A convenient procedure for the synthesis of 2-heterosubstituted statine derivatives as novel building blocks in HN-protease inhibitors has been developed. The synthesis starts with protected L-phenylalaninols, which were converted to gamma-amino alpha,beta-unsaturated esters in a one-pot procedure. A highly diastereoseletive epoxidation of the N-protected (E)-enoates, followed by regioselective ring opening of the corresponding 2,3-epoxy esters with a variety of heteronucleophiles, resulted in 2-heterosubstituted statine derivatives. The overall stereochemical outcome of the transformations meets the required configuration of HIV-protease inhibitors. The short, synthetically flexible, and highly diastereoselective synthesis of 2-heterosubstituted statines has enabled a broad derivation, covering the S3, S2, and S1'-S3' sites of the enzyme. In a series of 46 derivatives, several potent inhibitors were obtained with K-i values as low as 3.4 nM and antiviral activity in the lower nanomolar-range. The structural parameters of the compounds which determine the potency of inhibition and selectivity for the viral enzyme are discussed.