933791-92-5Relevant academic research and scientific papers
Enantioselective formation of tert-alkylamines by desymmetrization of 2-substituted serinols
Hong, Mi Sook,Kim, Tae Woo,Jung, Byunghyuck,Kang, Sung Ho
supporting information; experimental part, p. 3290 - 3296 (2009/04/10)
Novel enantioselective desymmetrization of 2-substituted 2-amino-1,3-propanediols has been established to generate asymmetric quaternary carbon centers comprising an amino group. Enantioselective as well as chemical conversion proved to be greatly dependent on the protecting group of the amino group in the substrate, desymmetrizing reagent, base, solvent, and naturally, catalyst. The highly effective desymmetrization has been implemented by using N-benzoylated substrates with benzoyl Chloride and triethylamine in the presence of tetraphenylbisoxazoline (24)-CuCl2 complex in THF at ambient temperature. An extensive survey of catalysts revealed that dimethylmalonate- bridged bisoxazoline-CuCl2 complexes were superior. Among them, the tetraphenylbisoxazoline (24)-CuCl2 complex turned out to work most efficiently with a wide array of the substrates. All the examined substrates, with the exception of 2-phenylserinol 36, were desymmetrized in the presence of 24-CuCl2 complex to give high enantioselectivities ranging from 85 to 95% ee. Complementary use of the diisopropylbisoxazoline (22)-CuCl2 complex has remedied the mediocre desymmetrization of 36 to give a significantly improved enantioselectivity from 63 to 83% ee.
Enantioselective synthesis of tertiary alcohols by the desymmetrizing benzoylation of 2-substituted glycerols
Jung, Byunghyuck,Hong, Mi Sook,Kang, Sung Ho
, p. 2616 - 2618 (2008/02/13)
(Chemical Equation Presented) Complementary catalysts have been found for the enantioselective desymmetrization of 2-substituted glycerols by monobenzoylation with benzoyl chloride and Et3N to give chiral tertiary alcohols with 80 to 94% ee (se
Synthesis of p-aminophenyl aryl H-phosphinic acids and esters via cross-coupling reactions: Elaboration to phosphinic acid pseudopeptide analogues of pteroyl glutamic acid and related antifolates
Yang, Yonghong,Coward, James K.
, p. 5748 - 5758 (2008/02/12)
(Chemical Equation Presented) The synthesis of suitably protected p-aminophenyl H-phosphinic acids and esters from the corresponding para-substituted aryl halides has been accomplished via the Pd-catalyzed cross-coupling reaction of anilinium hypophosphite, either in the absence or presence of a tetraalkyl orthosilicate, to provide the free H-phosphinic acid or the corresponding ester, respectively. Subsequent conjugate addition of either a PIII species or phosphorus anion, generated in situ from either the free H-phosphinic acid or ester, to a 2-methylene glutaric acid ester provided the aryl phosphinic acid analogue of p-aminobenzoyl glutamic acid. Alkylation of these suitably protected p-aminophenyl phosphinic acid esters with a 6-(bromomethyl)-pteridine or the corresponding (bromomethyl)pyridopyrmidine, followed by hydrolytic removal of protecting groups, provided the target aryl phosphinic acid analogues of folic acid and related antifolates. Alternatively, for the synthesis of the folate or 5-deazafolate analogues on a slightly larger scale, reductive amination with either N2-acetyl or N 2-pivaloyl-6-formylpterin or the corresponding formylpyridopyrmidine and the same suitably protected p-aminophenyl phosphinic acid esters, followed by removal of protecting groups, is preferred. In the course of this research, it was observed that the nucleophilicity of both the aniline nitrogen and various PIII species derived from p-aminophenyl phosphinic acid derivatives is significantly reduced compared to that of the unsubstituted counterpart.
