| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1345063 | Tetrahedron: Asymmetry | 2008 | 11 Pages |
The asymmetric addition of alkynylzinc reagents, prepared in situ from dimethylzinc and 1-alkynes, to α-dinitrones derived from glyoxal and N-(4-isopropylbenzyl)hydroxylamine was investigated by utilizing dicyclohexyl (R,R)-tartrate as a chiral auxiliary. The addition reaction of methyl(2-phenylethynyl)zinc afforded the corresponding optically active C2-symmetric (R,R)-bis(hydroxylamine) derivative with enantioselectivities of 90% and 81% ee by utilizing a stoichiometric and catalytic amount of the tartrate, respectively. Furthermore, the catalytic addition reaction of several alkynylzinc reagents also furnished the corresponding bis(hydroxylamine) with moderate to good enantioselectivities.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide
N,N′-[(R,R)-1,6-Diphenylhexa-1,5-diyne-3,4-diyl]bis[N-(4-isopropylbenzyl)hydroxylamine]C38H40N2O2Ee = 81%[α]D25=+14 (c 0.824, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-[(R,R)-1,6-Diphenylhexa-1,5-diyne-3,4-diyl]bis[N-(benzyl)hydroxylamine]C32H28N2O2Ee = 24%[α]D25=+7 (c 0.73, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-[(R,R)-1,6-Diphenylhexa-1,5-diyne-3,4-diyl]bis[N-(4-chlorobenzyl)hydroxylamine]C32H26N2O2Cl2Ee = 11%[α]D25=+5 (c 0.488, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-[(R,R)-1,6-Diphenylhexa-1,5-diyne-3,4-diyl]bis[N-(3,5-dimethylbenzyl)hydroxylamine]C36H36N2O2Ee = 47%[α]D25=+10 (c 0.584, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-[(R,R)-1,6-Diphenylhexa-1,5-diyne-3,4-diyl]bis[N-(4-t-butylbenzyl)hydroxylamine]C40H44N2O2Ee = 37%[α]D25=+5 (c 0.884, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-[(R,R)-1,6-Bis(4-pentylphenyl)hexa-1,5-diyne-3,4-diyl]bis[N-(4-isopropylbenzyl)hydroxylamine]C48H60N2O2Ee = 76%[α]D25=+13 (c 0.892, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-[(R,R)-1,6-Bis(4-methoxyphenyl)hexa-1,5-diyne-3,4-diyl]bis[N-(4-isopropylbenzyl)hydroxylamine]C40H44N2O4Ee = 72%[α]D25=+12 (c 0.788, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-{(R,R)-1,6-Bis[4-(trifluoromethyl)phenyl]hexa-1,5-diyne-3,4-diyl}bis[N-(4-isopropylbenzyl)hydroxylamine]C40H38N2O2F6Ee = 59%[α]D25=+9 (c 0.912, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-[(R,R)-1,6-Bis(2-fluorophenyl)hexa-1,5-diyne-3,4-diyl]bis[N-(4-isopropylbenzyl)hydroxylamine]C38H38N2O2F2Ee = 74%[α]D25=+11 (c 0.948, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-[(R,R)-Tetradeca-5,9-diyne-7,8-diyl]bis[N-(4-isopropylbenzyl)hydroxylamine]C34H48N2O2Ee = 79%[α]D25=-10 (c 0.248, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-[(R,R)-1,6-Bis(trimethylsilyl)hexa-1,5-diyne-3,4-diyl]bis[N-(4-isopropylbenzyl)hydroxylamine]C32H48N2O2Si2Ee = 70%[α]D25=-9 (c 0.536, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrateAbsolute configuration: (R,R)
N,N′-[(3R,4R)-1,6-Diphenylhexa-1,5-diyne-3,4-diyl] bis{N-(4-isopropylbenzyl)-O-[(1S′,4R′)-4,7,7-trimethyl-2-oxabicyclo[2.2.1]heptane-3-one-1-carbonyl]hydroxylamine}C58H64N2O8Ee = 100%[α]D25=+80 (c 0.14, EtOH)Source of chirality: dicyclohexyl (R,R)-tartrate, (1S,4R)-camphanic chlorideAbsolute configuration: (3R,4R,1S′,4R′)
