A simple synthetic route to access
racemic 3,3-disubstituted propylamines
in excellent yields (up to 95%) via Lewis acid catalyzed SN2-type ring opening of activated azetidines with electron-rich arenes
and heteroarenes under mild conditions has been accomplished. The
methodology is efficiently used for the racemic synthesis of an antimuscarinic
drug, tolterodine, in four steps in 47% overall yield.
Novel 3,4-dihydro-1,4-benzoxazine derivatives have been synthesized by an efficient and simple method in excellent enantio- and diastereospecificity (ee > 99%, de > 99%). The reaction proceeds via Lewis acid-catalyzed S2-type ring opening of activated aziridines with 2-halophenols followed by Cu(I)-catalyzed intramolecular C-N cyclization in a stepwise fashion under one-pot conditions to furnish the 3,4-dihydro-1,4-benzoxazine derivatives in excellent yields (up to 95%). The strategy offers a short and efficient synthesis to ( S)-3-methyl-1,4-benzoxazine ( S)-3v, a late stage intermediate in the synthesis of levofloxacin.
A route to 1,4-disubstituted tetrahydro-β-carbolines and tetrahydropyrano[3,4-b]indoles in high yields and stereoselectivity via SN2-type ring opening/Pictet–Spengler reaction of aziridines and epoxides with indoles is described.
A simple strategy for the synthesis of highly functionalized indolines via Lewis acid catalyzed ring-opening of activated aziridines with various nucleophiles followed by Cu(OAc)-mediated intramolecular C-H amination in one-pot has been developed with excellent enantio- and diastereospecificity (ee 99%; de >99%). The reaction proceeds via Cu(OAc)-catalyzed S2-type ring-opening of 2-phenyl-N-(2-pyridinesulfonyl)aziridine with alcohols and arene, followed by copper-mediated pyridine-2-sulfonamide directed intramolecular C(sp)-H activation/cyclization in a stepwise fashion to furnish the indoline derivatives in excellent yields (up to 91%).
A highly stereoselective asymmetric intermolecular conjugate addition of α-amino ester derivatives to cyclic enones via the memory of chirality (MOC) concept in high yields with excellent diastereo- and enantioselectivity (dr >99:1, up to 99% ee) is reported. The applicability and the generality of the strategy was demonstrated by its further exploration to acyclic α,β-unsaturated ketone and aromatic nitroalkenes, resulting in the formation of δ-keto-α-amino ester derivative and γ-nitro-α-amino ester derivatives, respectively, with excellent ee and dr.
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