221158-95-8

Upstream product

• 221158-93-6 2-benzyloxycarbonylamino-(1R,2S)-cyclobutane-1-carboxylic acid 
• 1140194-63-3 (-)-(1R,2S)-2-(t-butyloxycarbonylamino)cyclobutane-carboxamide 
• 221158-91-4 methyl 2-benzyloxycarbonylamino-(1R,2S)-cyclobutane-1-carboxylate 
• 770746-44-6 (-)-(1R,5aR,7aS)-1-phenyl-1,2,5a,6,7,7a-hexahydro-5H-cyclobuta[e][1,3]oxazolo[3,2-a]pyrimidin-5-one 
• 770746-46-8 (-)-(1S,6R)-2-[(1S)-1-phenylethyl]-2,4-diazabicyclo[4.2.0]octane-3,5-dione 
• 770746-48-0 (-)-(1S,6R)-2,4-diazabicyclo[4.2.0]octane-3,5-dione 

Downstream Products

• 868364-63-0 (-)-(1R,2S)-2-[(tert-butyloxycarbonyl)amino]cyclobutanecarboxylic acid 

Relevant academic research and scientific papers

An alkaloid-mediated desymmetrization of meso-anhydrides via a nucleophilic ring opening with benzyl alcohol and its application in the synthesis of highly enantiomerically enriched β-amino acids

The cinchona alkaloid-mediated opening of prochiral cyclic anhydrides in the presence of benzyl alcohol leading to optically active hemiesters is described. Structurally diverse anhydrides are converted into their corresponding benzyl monoesters with either enantiomer being obtained with up to 99 percent e.e. by using quinine or quinidine as the directing additive. A simple aqueous work-up protocol permits the isolation of the products in analytically pure form and the recovery of the alkaloids almost quantitatively. These hemiesters can be converted to N-protected β-amino esters by means of Curtius degradation of the corresponding acyl azides. Subsequent cleavage of both protecting groups by a single reaction step leads to the free β-amino acids in excellent yields. The efficiency of this procedure is demonstrated by the short asymmetric synthesis of the fungicide cis-pentacin delivering the amino acid with >99.7 percent enantiomeric excess.

Expedient preparation of all isomers of 2-aminocyclobutanecarboxylic acid in enantiomerically pure form

A short, convenient, gram scale protocol has been established to allow facile access to all four stereoisomers of 2-ami-nocyclobutanecarboxylic acid, each in enantiomerically pure form (ee >99%). Starting from the readily available cis racemate, the proce

[2+2] Photocycloadditions with chiral uracil derivatives: Access to all four stereoisomers of 2-aminocyclobutanecarboxylic acid

Starting from a single, chiral, bicyclic derivative of uracil, all four stereoisomers of 2-aminocyclobutanecarboxylic acid have been prepared in enantiomerically pure form, using a synthetic sequence which begins with a key photochemical [2+2] cycloaddition reaction and includes a practical cis to trans β-amino acid isomerisation procedure. Georg Thieme Verlag Stuttgart.

(+)- and (-)-2-aminocyclobutane-1-carboxylic acids and their incorporation into highly rigid β-peptides: Stereoselective synthesis and a structural study

Several derivatives of (+)- and (-)-2-aminocyclobutane-1-carboxylic acid, 1, have been prepared through enantiodivergent synthetic sequences. The stereoselective synthesis of free amino acid (+)-1 has been achieved, and this product has been fully charact

Synthesis of (+)-(1S,2R) and (-)-(1R,2S)-2-aminocyclobutane-1-carboxylic acids

(+)-(1S,2R) and (-)-(1R,2S)-2-aminocyclobutane-1-carboxylic acids have been prepared in >97% ee and in 33% and 20% overall yields starting from a single, chiral, bicyclic compound perceived as a chiral uracil equivalent. Construction of the cyclobutane ri

Enantioselective synthetic approaches to cyclopropane and cyclobutane β-amino acids: Synthesis and structural study of a conformationally constrained β-dipeptide

Synthetic approaches to carbocyclic compounds, namely cyclopropane and cyclobutane β-amino acids, are presented. One of them is based on enzymatic desymmetrization of meso diesters, leading to the enantioselective production of cis-hemiesters, which afforded β-amino acids through Curtius rearrangements. The enantiomeric excess for the cyclobutane derivatives was 91% whereas the cyclopropanes were obtained in 63% ee. According to another strategy, an enantiomerically pure cyclopropane trans-β-amino acid, bearing a quaternary center, has been synthesized from a homochiral precursor easily available from D-glyceraldehyde. The preparation and structural investigation of the first synthesized cyclobutane containing dipeptide is also described. A hairpin-like conformation of this molecule in the solid state has been demonstrated by X-ray structural analysis, showing crystal packing induced by the presence of the rigid cyclobutane moiety and the formation of intermolecular hydrogen bonds. NMR experiments confirmed that these molecules also tend to produce aggregates in solution. On the contrary, theoretical calculations suggest that intramolecular interactions are important in the gas phase, as expected. Copyright (C) 2000 Elsevier Science Ltd.

Stereoselective synthesis of (-)-(1R,2S)-2-aminocyclobutane-1-carboxylic acid, a conformationally constrained β-amino acid

The title compound as well as some derivatives have been synthesized for the first time in optically active form by means of a chemoenzymatic transformation used to induce asymmetry in achiral precursors. The enantio- and diastereomeric purity has been determined by HPLC and NMR techniques.