SYNTHESIS AND FIRST APPLICATIONS OF A NEW CHIRAL AUXILIARY (TERT-BUTYL 2-(TERT-BUTYL)-5,5-DIMETHYL-4-OXOIMIDAZOLIDINE-1-CARBOXYLATE)

doi:10.1002/HLCA.19950780512

Paper

SYNTHESIS AND FIRST APPLICATIONS OF A NEW CHIRAL AUXILIARY (TERT-BUTYL 2-(TERT-BUTYL)-5,5-DIMETHYL-4-OXOIMIDAZOLIDINE-1-CARBOXYLATE)

Published Aug 9, 1995 · A. Studer, T. Hintermann, D. Seebach

Helvetica Chimica Acta

Q2 SJR score

28

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0

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Abstract

Both enantiomers of tert-butyl 2-(tert-butyl)-5,5-dimethyl-4-oxoimidazolidine-1-carboxylate (11; Bbdmoic) were prepared from L-alanine (Schemes 1 and 2). The parent heterocycle, 2-tert-butyl-5,5-dimethylimidazolidin-4-one (12; from 2-aminoisobutyramide, H-Aib-NH2, and pivalaldehyde) was also available in both enantiomeric forms by resolution with O,O′-dibenzoyltartaric acid. The compound (R)- or (S)-11 was used as an auxiliary, but also as a chiral Aib building block in a dipeptide synthesis. The 3-propanoyl derivative 13 of (R)-11 was used for the preparation of enantiomerically pure 2-methyl-3-phenylpropanoic acid (enantiomer ratio (e.r.) 99.5:0.5), by benzylation of the Zn-enolate ( 14; Scheme 3). Oxidative coupling of the bis-enolate derived from heptanedioic acid and (S)-11 ( 23) and methanolysis of the auxiliary gave dimethyl trans-cyclopentane-1,2-dicarboxylate (26) with an e.r. of 93:7 (Scheme 5, Fig. 5). The 3-(Boc-Gly)-Bbdmoic derivative 29 was doubly deprotonated and, after addition of ZnBr2 alkylated with alkyl, benzyl, or allyl halides to give the higher amino-acid derivatives with excellent selectivities (e.r. > 99.5:0.5, Schemes 6 and 7). Michael additions of cuprates to [(E)-MeCHCHCO]-Bbdmoic 36 occurred in high yields, but high diastereoselectivities were only observed with aryl cuprates (diastereoisomer ratio (d.r.) 99:1 for R = Ph, Scheme 8). Finally, 3-(Boc-CH2)-Bbdmoic 17 was alkylated through the ester Li-enolate with primary and secondary alkyl, allyl, and benzyl halides with diastereoselectivities (ds) ranging from 91 to 98%, giving acetals of Boc-Aib-Xxx-O(t-Bu) dipeptides (Scheme 4). The effectiveness of Bbdmoic is compared with that of other chiral auxiliaries previously used for the same types of transformations.

Study Snapshot

The new chiral auxiliary (tert-butyl 2-(tert-butyl)-5,5-dimethyl-4-oxoimidazolidine-1-carboxylate) has been successfully synthesized and applied in various synthesis processes, with excellent selectivities and diastere

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

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Paper

SYNTHESIS AND FIRST APPLICATIONS OF A NEW CHIRAL AUXILIARY (TERT-BUTYL 2-(TERT-BUTYL)-5,5-DIMETHYL-4-OXOIMIDAZOLIDINE-1-CARBOXYLATE)

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References

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Citations

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Imidazolidinones and imidazolidine-2,4-diones show potential as potent antiviral agents against various viruses, including HIV, HCV, dengue, and EV71.

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