Chiral Ion-Pair Organocatalyst-Promoted Efficient Enantio-selective Reduction of α-Hydroxy Ketones
作者:Yiliang Zhang、Li He、Lei Shi
DOI:10.1002/adsc.201800053
日期:2018.5.16
The enantioselective reduction of α‐hydroxy ketones with catecholborane has been developed employing 5 mol% of an 1,1′‐bi‐2‐naphthol (BINOL)‐derived ion‐pair organocatalyst. This methodology provides a straightforwardaccess to the corresponding aromatic 1,2‐diols in high yields (up to 90%) with excellent enantioselectivities (up to 97%). Furthermore, the α‐amino ketones also could be reduced with
A number of opticallyactive amino alcohols were synthesized by direct asymmetric transfer hydrogenation of the corresponding amino ketones with good-to-high enantiomeric excesses (up to 95%) and excellent yields (up to 93% ). When the range of substrates was broadened to include α-sulfonamido ketones or α-keto sulfones, the corresponding products were obtained with 100% enantiomeric excesses. The
peroxide (DTBP)-promoted α-alkylation of α-amino carbonyl compounds by simple alkanes is developed, proceedingthrough dual sp3 C–H bonds cleavage. The reaction was applicable for α-amino ketones and α-amino esters, providing a facile pathway for the α-functionalization of these substrates. The radical pathway is involved in this transformation.
A direct method for the synthesis of 1,3,4-triarylpyrroles was achieved easily from cyclization of α-amino carbonylcompounds and aldehydes catalyzed by I2. Various substituted groups can be employed, and this reaction can proceed smoothly in moderate to good yields.
An efficient one-pot synthesis of substituted quinolines from alpha-arylamino ketones in the presence of PBr3 in DMF has been developed. This general protocol provides a novel and facile access to substituted quinolines by sequential Vilsmeier-Haack reaction, intramolecular cyclization and aromatization reactions of alpha-arylamino ketones. PBr3 plays a dual role in the quinoline synthesis: as a key