869378-13-2Relevant 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.
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.
A one-pot diastereoselective synthesis of cis-3-hexene-1,6-diols via an unusually reactive organozinc intermediate
Garcia, Celina,Libra, Eric R.,Carroll, Patrick J.,Walsh, Patrick J.
, p. 3210 - 3211 (2007/10/03)
A highly diastereoselective method for the synthesis of cis-3-hexene-1,6-diols has been developed. This new reaction proceeds with excellent control of diastereoselectivity over four stereocenters and the double bond geometry. The diols are made in a one-pot procedure involving hydroboration of a terminal alkyne and transmetalation to zinc to give a divinylzinc intermediate. This intermediate undergoes reductive elimination, forming a C=C bond. In the absence of a trapping reagent, diene is liberated (70% yield); however, in the presence of ketones or aldehydes, the proposed intermediate metallocyclopentene is trapped via a double insertion of the carbonyl substrate. Workup provides the diols in 47-86% yield. Copyright
