A new synthesis of β-amino acids by use of ketene diethyl acetal as enolate equivalent

α-Amido Sulfones as Stable Precursors of ReactiveN-Acylimino Derivatives

“…N -Formylarylimines derived from sulfones 34 are reactive enough to produce N -formyl-β-amino esters 109 upon reaction with ketene diethyl acetate 108 (Scheme ) 32 …”

“…81 N-Formylarylimines derived from sulfones 34 are reactive enough to produce N-formyl-β-amino esters 109 upon reaction with ketene diethyl acetate 108 (Scheme 32). 82 Chiral R-diazocarbonyl derivatives can be deprotonated at the 2-position and made to react with various aryl N-tosylimines. However, reaction of diazo compound 110 with aliphatic N-tosylimines is possible only using N-tosylbutyltolyl sulfone 111 that in basic conditions is transformed into the corresponding N-tosylbutylimine giving adduct 112 (Scheme 33).…”

Asymmetric and Geometry‐Selective α‐Alkenylation of α‐Amino Acids

“…Three methods for the synthesis of N’ ‐alkenylureas, are shown in Scheme . Starting materials 3 lacking a 1‐substituent were most readily prepared by the sulfinate‐promoted condensation of the urea 8 with an aldehyde (Method a) . This method failed with ketones, so 1,1‐disubstituted alkenes (e.g., 3 m ) were instead made by acylation of an N ‐methyl ketimine with the carbamoyl chloride 9 .…”

Recent Developments in the Synthesis of β‐Amino Acids

“…Making use of an addition reaction on racemic substrates and a subsequent enzymatic resolution, Rossen et al [84] described the enantioselective synthesis of several b 2 -amino acids. This protocol involves the addition of ketene diethyl acetal to an in situ prepared acyl imine.…”