Bicyclic Lactams Derived from Serine or Cysteine and 2-Methylpropanal

Abstract

Bicyclic lactams may be prepared from serine or cysteine and 2-methylpropanal; the resulting S,N-heterocycles are more stable than the corresponding O,N-heterocycles but both are synthetic intermediates capable of further elaboration.

Use of an asparaginyl endopeptidase for chemo-enzymatic peptide and protein labeling

“…The 1,2-aminothiol functionality of N-terminal cysteine contains two nucleophilic centers, and thus it can react with aldehydes to form thiazolidinones. 51 – 54 2-Formyl phenylboronic acid (FPBA) is one such electrophile that reacts with N-terminal cysteine with exquisite selectivity and efficiency. 53 , 54 With biomolecular rate constant measured up to 10 5 M –1 s –1 , FPBA and its derivatives have been used for polypeptide labeling.…”

Tetramate derivatives by chemoselective Dieckmann ring closure ofallo-phenylserines, and their antibacterial activity

“…The chemoselectivity of this cyclisation depends upon the identity of R 1 , R 2 , X, along with the 2,5-relative stereochemistry of the N-acyloxazolidine or thiazolidine starting material 1. Normally, Path A mode of cyclisation is preferred and predominates for 2,5-cis-malonyloxazolidines (X=O, R 1 = t Bu, R 2 =H/Me) derived from serine 5,6 and threonines 7,8 leading to tetramates 2, although 2,5-trans-malonyloxazolidines (X=O) if formed, usually close by Path B leading to tetramates 3. This intrinsic chemoselectivity may be controlled in some cases by adjusting the conditions for the Dieckmann cyclisation, thus tetramates (X=O, R 2 =H) arising by Path A were most readily accessed in good yield using the reaction conditions (KO t Bu (1.1 eq), dry t BuOH, reflux), while those from Path B were available by the use of alternate conditions (KO t Bu (2.2 eq), wet t BuOH, reflux).…”

Stereoselectivity of thiazolidine, malonamides and bicyclic tetramates with isopropyl NH and SH protecting group

“…Bicyclic tetramates, which may exhibit biological activity, are accessible by stereoselective Dieckmann ring closure reaction. We have shown this cyclization (Scheme 1) to get 4 and utilization of the cyclized product 4 to synthesize a library of compounds for a number of systems (Andrews et al, 1998;Bagum et al, 2019aBagum et al, , 2019bBagum et al, , 2020Saney et al, 2023).…”

“…The structures of these novel compounds were determined by NMR and MS analysis. Previous works (Anwar et al, 2010;Bagum et al, 2019aBagum et al, , 2020Saney et al, 2023) on this field has extensive examples with different NH and SH protecting groups including t-Bu and aryl systems. Herein, we have examined thiazolidine, malonamides and bicyclic tetramates with isopropyl NH and SH protecting group.…”