215546-92-2Relevant academic research and scientific papers
Reagent- and chelation-controlled diastereoselective aziridination of electron-rich alkenes by 3-acetoxyamino-2-(1-hydroxy-2,2-dimethylprop-1-yl)-quinazolin-4(3H)-one
Atkinson, Robert S.,Gattrell, William T.,Ayscough, Andrew P.,Raynham, Tony M.
, p. 1935 - 1936 (1996)
In the presence of titanium(iv) tert-butoxide, the title 3-acetoxyaminoquinazolinone aziridinates styrene, butadiene and indene completely diastereoselectively; the absolute configuration of the styrene-derived aziridine 6a is proven by X-ray crystallogra
3-Aminoquinazolinones as chiral ligands in catalytic enantioselective diethylzinc and phenylacetylene addition to aldehydes
Karabuga, Semistan,Karakaya, Idris,Ulukanli, Sabri
, p. 851 - 855 (2014/06/23)
A series of readily known enantiomerically pure 3-aminoquinazolinones 1a-d were synthesised from easily accessible chiral pool α-hydroxy acids and α-amino acids in only four steps without any requirement of chromatography. These quinazolinones were examined as chiral ligands for catalytic enantioselective diethylzinc and phenylacetylene additions to aldehydes. For enantioselective alkylations, the effects of temperature, solvent, diethylzinc and ligand criteria were analysed, and the desired chiral alcohols were obtained in up to 86% ee. 3-Aminoquinazolinones 1a-d were also shown to be very useful ligands in enantioselective alkynylations of aldehydes. Based upon the optimised conditions, the corresponding propargylic alcohols were obtained in up to 94% ee.
Diastereoselective aziridination of alkenes using 3-acetoxyamino-2-(1-hydroxyalkyl)quinazolin-4(3H)-ones in the presence of titanium(IV) tert-butoxide
Atkinson, Robert S.,Ayscough, Andrew P.,Gattrell,Raynham, Tony M.
, p. 2783 - 2793 (2007/10/03)
3-Amino-2-[(S)-1-hydroxy-2,2-dimethylpropyl]quinazolin-4(3H)-one 9 (Q2NH) was prepared in four steps from (S)-tert-leucine in 43% yield without the need for chromatography. The corresponding 3-acetoxy-aminoquinazolinone 10 (Q2NHOAc), prepared in dichloromethane solution by reaction of 9 with lead tetraacetate, reacts with alkenes in the presence of titanium(IV) tert-butoxide to give the corresponding aziridines diastereoselectively. With styrene and butadiene the corresponding aziridines 12a (65%) and 15a (85%) are obtained completely diastereoselectively. Indene gave the expected endo-N-invertomer of aziridine 16a as the kinetically-formed product (86%) also completely diastereoselectively: equilibration to give a 8:1 ratio of exo:endo N-invertomers occurs above 0°C. From an X-ray structure determination of aziridine 12a, the sense of diastereoselectivity in its formation is in agreement with the transition state model 14. Aziridinations of methyl acrylate and of tert-butyl acrylate give respectively 23a (65%) and 24a (53%), highly diastereoselectively (dr ≥ 20:1) and with the same sense of diastereoselectivity as identified by an X-ray crystal structure determination on 24a and chemical correlation of esters 23a and 24a via the acid 25. Aziridinations of α-methylstyrene and methyl methacrylate are less completely diastereoselective; isoprene reacts completely diastereoselectively at its unsubstituted double bond but with little diastereoselectivity at its methyl-substituted double bond and the regioselectivity of aziridination on the two double bonds is 1.4:1 respectively by comparison to 1:4.7 in the absence of titanium(IV) tert-butoxide.
