Cyclopropenimine-Catalyzed Enantioselective Mannich Reactions of <i>tert</i>-Butyl Glycinates with <i>N</i>-Boc-Imines
作者:Jeffrey S. Bandar、Tristan H. Lambert
DOI:10.1021/ja407277a
日期:2013.8.14
shown to catalyze Mannichreactions between glycine imines and N-Boc-aldimines with high levels of enantio- and diastereocontrol. The reactivity of 1 is shown to be substantially greater than that of a widely used thiourea cinchona alkaloid-derived catalyst. A variety of aryl and aliphatic N-Boc-aldimines are effective substrates for this transformation. A preparative-scale reaction to deliver >90 mmol
Development of New Catalytic Asymmetric Routes toward a Cost-Driving Building Block of Nirmatrelvir
作者:Robert Szpera、Shanjun Huang、Harriet A. M. Fenton、William Waddington、Adam E. S. Gymer、Ian B. Moses、Julia Buck、Heather Ingram、Steven J. Fussell、Robert Walton、Charles S. Shanahan、Sarah L. Aleshire、Juliana M. S. Robey、Hanuman P. Kalmode、Michel C. Nuckols、Nageswara R. Kalikinidi、Venumadhav Janganati、Sipak Joyasawal、Chanaka M. Amarasekarage、Chris H. Senanayake、B. Frank Gupton
DOI:10.1021/acs.oprd.4c00109
日期:2024.7.19
cost-driving lactam-containing fragment with two stereogenic centers. Our goal was to help decrease the cost of nirmatrelvir by developing a scalable low-cost synthesis of this fragment, avoiding the use of cryogenic conditions reported in the initial route. Herein, we disclose three catalytic asymmetric routes toward this fragment, via (i) chiral Lewis acid (copper) catalysis, (ii) chiral Bro̷nsted base organocatalysis
Enantioselective Brønsted Base Catalysis with Chiral Cyclopropenimines
作者:Jeffrey S. Bandar、Tristan H. Lambert
DOI:10.1021/ja3015764
日期:2012.3.28
Cyclopropenimines are shown to be a highly effective new class of enantioselective Bronsted base catalysts. A chiral 2,3-bis(dialkylamino)cyclopropenimine catalyzes the rapid Michael reaction of a glycine imine substrate with high levels of enantioselectivity. A preparative scale reaction to deliver 25 g of product is demonstrated, and a trivial large scale synthesis of the optimal catalyst is shown. In addition, the basicity of a 2,3-bis(dialkylamino)cyclopropenimine is measured for the first time and shown to be approximately equivalent to the P-1-tBu phosphazene base. An X-ray crystal structure of the protonated catalyst is shown along with a proposed mechanistic and stereochemical rationale.