136035-57-9

Upstream product

• 917-92-0 3,3-Dimethylbut-1-yne 
• 1568-65-6 bis(cyclohexanyl)borane 
• 110-83-8 cyclohexene 
• 13601-86-0 1-bromo-3,3-dimethyl-1-butyne 

Downstream Products

• 140148-22-7 (S)-4,4-dimethyl-1-phenyl-(E)-pent-2-en-1-ol 

Relevant academic research and scientific papers

One-pot asymmetric synthesis of acyclic chiral epoxy alcohols via tandem vinylation - Epoxidation with dioxygen

(Chemical Equation Presented) We have developed a one-pot procedure for the asymmetric synthesis of a synthetically challenging class of acylic secondary epoxy alcohols with three contiguous stereocenters from simple achiral starting materials. The epoxy alcohols are synthesized via a tandem catalytic asymmetric vinylation of an aldehyde coupled with a diastereoselective epoxidation reaction. A vinylzinc reagent generated in situ undergoes enantioselective addition to an aldehyde in the presence of a zinc catalyst to provide an allylic zinc alkoxide. This species is then epoxidized by addition of dioxygen and a titanium tartrate catalyst to give epoxy alcohols with excellent enantioselectivities, in most cases, and with diastereoselectivities up to 4.5:1 in favor of the threo-diastereomer. The system described herein represents a significant advance in terms of synthetic efficiency and selectivity.

A positional scanning approach to the discovery of dipeptide-based catalysts for the enantioselective addition of vinylzinc reagents to aldehydes

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

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

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

(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.

Stereoselective dehalogenation of (Z)-1-halo-1-alkenyldialkylborane with tributyltin hydride: The behavior of tributyltin hydride as a hydride donor

The reaction of (Z)-1-halo-1-alkenyldialkylborane (1) with tributyltin hydride (n-Bu3SnH) at 0°C or room temperature results in reductive removal of the halogen atom to afford (E)- or (Z)-1-alkenyldialkylborane whose stereochemistry depends on the dialkylboryl group and the alkenyl group of 1.