Separation of (R)- and (S)-tert-butyl 2-tert-butyl-4-methoxy-2,5-dihydro-1,3-imidazole-1-carboxylate (building block for amino acid synthesis) by preparative high performance liquid chromatography on a polysaccharide stationary phase

Racemic and enantiopure 2‐tert‐butyltetrahydropyrimidinones (from pivalaldehyde and 3‐aminocarboxylic acids) are converted to Alloc‐, Boc‐, and Z‐protected cyclic imino esters (7–10, Schemes 2–4). These are deprotonated to Li enaminates (K, L). Reactions with electrophiles (prim., sec. alkyl, allyl, benzyl, propargyl halides, aldehydes, imines, enoates) give good yields and are highly diastereoselective (products 11–42, Schemes 5–10). A two‐step cleavage (removal of protecting group and hydrolysis) under very mild conditions converts the heterocyclic products to α‐branched β‐amino acid methyl esters (43–61, Schemes 11–13). The structure of the products is determined by NMR spectroscopy (Figure 1), by chemical correlation (Scheme 14), and by X‐ray analysis (Figure 2, 3, 7, Table 1). A structure of the Li enaminates is proposed (Figure 4). Mechanistic models are derived for the reactions occurring with formation of two stereogenic centers with relative topicity like (Figures 5, 6).

show abstract

Determination of enantiomeric composition of (−)‐(R)‐2‐tert‐butyltetrahydroimidazolidin‐4‐one by polarimetry, ¹H NMR, and chiral SFC

Garcı́a-Martı́nez

Hernández

Biba

et al. 2005

Chirality

View full text Add to dashboard Cite

Partial resolution of rac-2-tert-butyltetrahydroimidazolidin-4-one was carried out by recrystallization of diastereomeric salts. The enantiomeric composition of enriched samples was estimated by polarimetry, (1)H NMR, and chiral SFC. Enantiomeric composition estimated by polarimetry or by (1)H NMR was directly proportional to that estimated by chiral SFC. The occurrence of solute self-association in chloroform was detected through measurements of optical and specific rotation at variable concentration of (-)-(R)-2-tert-butyltetrahydroimidazolidin-4-one. Our data suggest that solute self-association in chloroform might be independent of enantiomeric composition.

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

customersupport@researchsolutions.com

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Separation of (R)- and (S)-tert-butyl 2-tert-butyl-4-methoxy-2,5-dihydro-1,3-imidazole-1-carboxylate (building block for amino acid synthesis) by preparative high performance liquid chromatography on a polysaccharide stationary phase

Cited by 9 publications

References 26 publications

Preparation and Use in Amino Acid Synthesis of a New Chiral Glycine Derivative – (R)- and (S)-tert-Butyl 2-tert-Butyl-4-methoxy-2,5-dihydroimidazole-1-carboxylate (BDI)⋆

Preparation and Use in Amino Acid Synthesis of a New Chiral Glycine Derivative – (R)- and (S)-tert-Butyl 2-tert-Butyl-4-methoxy-2,5-dihydroimidazole-1-carboxylate (BDI)⋆

EPC-Synthesis of β-Amino Acid Derivatives through Lithiated Hydropyrimidines

Determination of enantiomeric composition of (−)‐(R)‐2‐tert‐butyltetrahydroimidazolidin‐4‐one by polarimetry, ¹H NMR, and chiral SFC

Contact Info

Product

Resources

About

Separation of (R)- and (S)-tert-butyl 2-tert-butyl-4-methoxy-2,5-dihydro-1,3-imidazole-1-carboxylate (building block for amino acid synthesis) by preparative high performance liquid chromatography on a polysaccharide stationary phase

Cited by 9 publications

References 26 publications

Preparation and Use in Amino Acid Synthesis of a New Chiral Glycine Derivative – (R)- and (S)-tert-Butyl 2-tert-Butyl-4-methoxy-2,5-dihydroimidazole-1-carboxylate (BDI)⋆

Preparation and Use in Amino Acid Synthesis of a New Chiral Glycine Derivative – (R)- and (S)-tert-Butyl 2-tert-Butyl-4-methoxy-2,5-dihydroimidazole-1-carboxylate (BDI)⋆

EPC-Synthesis of β-Amino Acid Derivatives through Lithiated Hydropyrimidines

Determination of enantiomeric composition of (−)‐(R)‐2‐tert‐butyltetrahydroimidazolidin‐4‐one by polarimetry, 1H NMR, and chiral SFC

Contact Info

Product

Resources

About

Determination of enantiomeric composition of (−)‐(R)‐2‐tert‐butyltetrahydroimidazolidin‐4‐one by polarimetry, ¹H NMR, and chiral SFC