Preparation and Reactivity of Versatile α-Amino Ketones

Abstract

Many challenges of chemoselectivity arise from the requirement to manipulate incompatible functional groups. Synthetic methods that do not rely on protecting groups are of strategic significance to chemical synthesis. Particularly valuable are molecules with reactive functionalities that are kinetically stabilized against inter- or intramolecular reactions with each other. We have developed a simple access to molecules that contain both ketone and N-H aziridine functionalities. These compounds were found to undergo highly selective reduction and carbonyl addition reactions, making them versatile precursors to complex amines.

Overcoming the Demons of Protecting Groups with Amphoteric Molecules

“…Accordingly, unprotected aziridine aldehydes were prepared by simple reduction of aziridine esters (Scheme ) 14. 15 Upon formation, the aziridine aldehydes dimerize to give stable products that were found to act as aldehydes under suitable reaction conditions. In doing so, we have generated bench‐stable molecules equipped with secondary amine and aldehyde functionalities that resist iminium ion formation from the dimeric amino acetal adduct.…”

Stereocontrolled Total Syntheses of (−)‐Rotenone and (−)‐Dalpanol by 1,2‐Rearrangement and SNAr Oxycyclizations

“…We arbitrarily installed the DE ring first, followed by the A ring, which led us to several interesting findings. The fluorobenzene 8 was lithiated and combined with the chiral, non‐racemic epoxy amide 9 , thus giving epoxy ketone 10 in 72 % yield. The bromide 11 was subjected to bromine–lithium exchange and combined with the ketone 10 .…”

The Growing Synthetic Utility of the Weinreb Amide

“…The aziridine carboxamides 79a and 79b are easily prepared from the corresponding aziridine-2-carboxylate esters and are convenient equivalents for aziridine aldehydes and 2-keto aziridines. 67 Aziridine aldehydes 83 and 2-keto aziridines 84 are fine examples of compounds displaying amphoterism, 68 wherein amine and carbonyl functionalities are kinetically stabilized against inter-or intramolecular reactions and thereby orthogonal (no amine protection is required).…”