A Novel Route to N-Alkylated Derivatives of Aziridine-2-Carboxylic Acid. an Alternative Synthesis of (S,S)-Bz-Azy-Val-OMe

The Synthesis of (2R)-Aziridine-2-carboxylic Acid Containing Dipeptides

“…This approach is reportedly less efficient because several various by-products are formed in the cyclization step. 27,28,37,39,47 The second more efficient strategy, which starts from the aziridine-2-carboxylic acid, was therefore used. 34,39,48 The synthesis of N-terminal aziridine containing dipeptides 2a-e was straightforward and high yielding.…”

“…36,37 Nonetheless, up to now, literature reports on the preparation of partially or fully deprotected dipeptide derivatives have been rare. To the best of our knowledge, there has been only one report by Korn 36 describing the synthesis of fully deprotected H-Azy-Leu-OH and only a couple of papers describing the synthesis of N-deprotected 21,27,38,39 and C-deprotected dipeptides. 34,36 Most of them suffer from low isolated yields following work-up and chromatography which reflects the inherent instability of these compounds.…”

Asymmetric Syntheses with Aziridinecarboxylate and Aziridinephosphonate Building Blocks

“…Michael addition of amines to a-halo-a,b-unsaturated esters and derivatives gives rise to a-halo-b-amino esters, which often undergo spontaneous cyclization to aziridine-2-carboxylates [23][24][25][26][27][28]. The diastereoselectivity of this process is not usually satisfactory, but high asymmetric induction could be achieved through careful choice of chiral directing group and reaction conditions.…”

“…The key stereodifferentiating step involved a face-selective protonation of enolate 18 to give a-bromo-b-amino amides 19, which then cyclized under the reaction conditions to give aziridines 20. Amines also react with a,b-dibromo esters to give aziridine-2-carboxylates [23][24][25][29][30]. Here it has been suggested that initial formation of an a-bromoa,b-unsaturated ester through base-promoted elimination, followed by Michael addition of the amine, gives rise to an a-bromo-b-amino ester, followed by aziridine ring-formation [24].…”

An efficient and general procedure for room-temperature synthesis of benzofurans under solvent-free conditions using KF/Al2O3

“…In recent years, potassium fluoride on alumina (KF/Ab03) [18] has emerged as an environmentally friendly and very powerful solid phase reagent for various organic functional manipulations such as ring closure reactions [19], epoxidation of alkenes [20], ether synthesis [21], amide [22] and amine [23] chemistry, Michael addition [24], aldol condensation [25], alkene synthesis [26], rearrangement processes [27], and cycloaddition reactions [28]. A number of advantages are associated with the use of this reagent like avoiding the …”