2000
DOI: 10.1039/b005814i
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Abstract: The title compounds diacylaminoquinazolinones (DAQs) are enantioselective acylation agents for amines and a detailed study of their stereostructures was undertaken with the aim of understanding how this enantioselectivity arises. The N-N bond in these DAQs is a chiral axis. Even where both N-acyl groups are (S)-2-acetoxypropanoyl, the N-N bond is still a chiral axis because in the most stable conformation of the planar imide moiety, one exo/endo orientation of the carbonyl groups is much preferred over the alt… Show more

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Cited by 22 publications
(30 citation statements)
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“…The reaction provided b-keto amide 15a and b-hydroxy amide 16a, which were separated by flash column chromatography and converted to the free amines by treating either b-keto amide 15a or b-hydroxy amide 16a with an excess of LiAlH 4 in refluxing dioxane. Conversion of the amines to their Mosher amides did not allow the estimation of the enantiomeric excess by 19 by the acylation of commercially available (S)-2-methylpiperidine with benzoyl chloride, allowing the assignment of the absolute configuration of the resolved amines.…”
Section: Resultsmentioning
confidence: 98%
“…The reaction provided b-keto amide 15a and b-hydroxy amide 16a, which were separated by flash column chromatography and converted to the free amines by treating either b-keto amide 15a or b-hydroxy amide 16a with an excess of LiAlH 4 in refluxing dioxane. Conversion of the amines to their Mosher amides did not allow the estimation of the enantiomeric excess by 19 by the acylation of commercially available (S)-2-methylpiperidine with benzoyl chloride, allowing the assignment of the absolute configuration of the resolved amines.…”
Section: Resultsmentioning
confidence: 98%
“…For example, kinetic resolution of a (rac)-α-amino ester derivative using 0.5 equivalent of chiral reagent resulted in selective benzoylation of its (S)-enantiomer to afford amide in 94% ee and unreacted (R)-amine in 92% ee (Figure 68(b)). 415 Mioskowski and coworkers have employed a chiral disulfonamide as a reagent for the enantioselective Nacylation of a range of (rac)-amines in DMPU at −20°C, affording chiral amides with good levels of stereocontrol (Figure 68(c)). 416 A chiral benzimidazole has been used for the enantioselective benzoylation of a series of α-amino esters in THF at −10°C, affording (R)-N-benzoylamides in 89-91% ee at approximately 50% conversion (Figure 68(d)).…”
Section: Redox Amidation Reactionsmentioning
confidence: 97%
“…417 Bode and coworkers have recently employed a recyclable polymer-supported acylating reagent derived from chiral hydroxamic acids for the kinetic resolution of a wide range of N-heterocycles that contain secondary amino groups in good-to-excellent ee (Figure 68(e) Figure 68 Kinetic resolution of (rac)-amines using acylating agents that contain a stereodirecting leaving group. [414][415][416][417][418] Kinetic resolution strategies involving stereoselective derivatization of a (rac)-amine with chiral acylating agents that afford diastereomeric amide products have also been developed. An impressive example of this approach involves reaction of (rac)-secondary amines with (S)-naproxen chloride, resulting in the selective N-acylation of its (S)-enantiomer to afford an (S,S)-amide in 87% de (Figure 69).…”
Section: Redox Amidation Reactionsmentioning
confidence: 99%
“…the preferred orthogonal arrangement found in DAQS [6][7][8][9][10][11] . This unfavourable interaction could provide an inherent stereoelectronic barrier to ringformation.…”
Section: Stereostructures Of Pyridazinonequnazolinone 7 and 15mentioning
confidence: 99%
“…We have shown previously that 3-diacylaminoquinazolin-4(3H)-ones, when the two acyl groups on the exocyclic nitrogen are different, the N-N bond is a chiral axis with the two planes containing the quinazolinone and imide moieties orthogonal to one another [6][7][8][9][10] . The barrier to N-N bond rotation is sufficiently high to allow separation of diastereoisomers (atropisomers) as in 2 [11] .…”
Section: Introductionmentioning
confidence: 99%