62072-20-2Relevant academic research and scientific papers
Catalytic enantioselective synthesis of secondary allylic alcohols from terminal alkynes and aldehydes via 1-alkenylboron reagents
Shono, Takashi,Harada, Toshiro
supporting information; experimental part, p. 5270 - 5273 (2011/02/24)
A practical one-pot method has been developed for preparing enantioenriched secondary allylic alcohols starting from terminal alkynes and aldehydes. Hydroboration of terminal alkynes with dicyclohexylborane and subsequent reaction of the resulting alkenylboron reagents with aldehydes in the presence of a catalytic amount (5 mol %) of 3-(3,5-diphenylphenyl)-H8-BINOL and excess titanium tetraisopropoxide afforded the corresponding allylic alcohols in high enantioselectivities up to 94% ee.
Construction of terminal conjugated enynes: Cu-mediated cross-coupling reaction of alkenyldialkylborane with (trimethylsilyl)ethynyl bromide
Hoshi, Masayuki,Kawamura, Noritsugu,Shirakawa, Kazuya
, p. 1961 - 1970 (2007/10/03)
The cross-coupling reaction of (E)- and (Z)-alk-1-enyldialkylborane with (trimethylsilyl)ethynyl bromide proceeds in the presence of a catalytic amount of copper(II) acetylacetonate and a base under extremely mild conditions to provide conjugated enynes w
A positional scanning approach to the discovery of dipeptide-based catalysts for the enantioselective addition of vinylzinc reagents to aldehydes
Sprout, Christopher M.,Richmond, Meaghan L.,Seto, Christopher T.
, p. 7408 - 7417 (2007/10/03)
A combinatorial library of dipeptide N-acylethylenediamine-based ligands was synthesized by parallel solid-phase methods. These ligands were screened in crude form as catalysts for the asymmetric addition of vinylzinc reagents to aldehydes to give chiral allylic alcohols. Three sites of diversity on the ligands were optimized using a positional scanning approach. The optimized structure from the library, ligand 54, was found to catalyze the formation of 10 different (E)-allylic alcohols with enantioselectivities ranging from 90% to 95% ee. This ligand was effective for both aromatic and α-branched aldehydes, and vinylzinc reagents derived from both bulky and straight chain terminal alkynes.
Enantioselective addition of vinylzinc reagents to aldehydes catalyzed by modular ligands derived from amino acids
Richmond, Meaghan L.,Sprout, Christopher M.,Seto, Christopher T.
, p. 8835 - 8840 (2007/10/03)
A series of N-acylethylenediamine-based ligands were synthesized from Boc-protected amino acids. The ligands were screened for the ability to catalyze the asymmetric addition of vinylzinc reagents to aldehydes. Three sites of diversity on the ligands were optimized for this reaction using a positional scanning approach. The optimized ligand 3d was found to catalyze the formation of 15 different (E)-allylic alcohols with enantioselectivities that ranged from 52 to 91% ee and yields that ranged from 40 to 90%. This ligand was especially effective for the reaction of aromatic aldehydes with vinylzinc reagents derived from bulky terminal alkynes. Ligand 3d catalyzed the addition of (E)-(3,3-dimethylbut-1-enyl)(ethyl)zinc to 2-naphthaldehyde to give (R,E)-4,4-dimethyl-1-(naphthalene-1-yl)pent-2-en-1-ol in 89% ee. The ee of this product could be increased to 97% through a single recrystallization.
Solid-phase synthesis of chiral N-acylethylenediamines and their use as ligands for the asymmetric addition of alkylzinc and alkenylzinc reagents to aldehydes
Sprout, Christopher M.,Richmond, Meaghan L.,Seto, Christopher T.
, p. 6666 - 6673 (2007/10/03)
A solid-phase procedure has been developed for the synthesis of chiral N-acylethylenediamine ligands. The ligands are obtained in good yield and purity, without the need for chromatography or other purification methods. Several new and previously reported ligands were prepared using this procedure. These compounds were examined as catalysts for the enantioselective addition of alkylzinc reagents to aldehydes. In all cases, the crude ligands from the solid-phase syntheses catalyzed the reactions with similar yields and stereoselectivities when compared to reactions using ligands that had been purified by standard methods. Preliminary studies were also performed with ligands 3a and 3f as catalysts for the addition of alkenylzinc reagents to aldehydes to give chiral allylic alcohols. Ligand 3f was found to catalyze this addition reaction in up to 76% ee.
[2,2]paracyclophane-based N,O-ligands in alkenylzinc additions to aldehydes
Dahmen, Stefan,Braese, Stefan
, p. 4119 - 4122 (2007/10/03)
(matrix presented) The application of planar and central chiral [2,2]paracyclophane-based N,O-ligands in asymmetric alkenylzinc additions to various aldehydes is described, which gives rise to very high ee's especially for difficult substrates. A fine-tuning of the alkenylzinc species by employing different transmetalation reagents is reported, allowing control of the steric bulk of the alkenylzinc species and thus the selectivity of the catalysis.
