Homoallylic Alcohols In Good Yields Research Articles

A chiral oxazoline for catalytic enantioselective Nozaki-Hiyama-Kishi allylation and vinylation of aldehydes

Asymmetric allylation and vinylation of aldehydes with allyl halides and vinyl halides have been achieved using the chromium(II)-oxazoline catalyst. The catalyst promotes the highly efficient enantioselective Nozaki–Hiyama-Kishi (NHK) allylation of aldehydes using allyl bromide, producing the corresponding homoallylic alcohols in good yields (up to 84%) and a high level of enantioselectivity (up to 98% ee). Meanwhile, the NHK vinylation of aldehydes produce desired allylic alcohols in satisfactory yields (up to 88%) and a high level of enantioselectivity (up to 97% ee). We developed a reliable and milder protocol for preparing chiral homoallylic and allylic alcohols.

Preparation of Bifunctional Allylboron Reagent and Application to Aldehyde Allylboration

Synthesis of a bifunctional allylboron reagent via Ni-catalyzed borylation of allylic acetate is reported. Subsequent allylation of aldehydes gave homoallylic alcohols in good yields. The allylsila...

Neighboring Hydroxyl Group-Assisted Allylboration and Lewis Acid-Mediated Carbonyl-Ene Reaction for Access to a Hapalindole Cyclohexane Core with Multiple Contiguous Stereogenic Centers.

A neighboring hydroxyl group-assisted allylboration of 3-indolyl ketones with γ,γ-disubstituted allylboronic acids is reported, affording various 3-indolyl-substituted homoallylic alcohols in good yields with excellent diastereoselectivies (up to >20:1 dr). The hydroxyl group not only played a vital role in the challenging allylboration but was elaborated for the subsequent construction of a hapalindole cyclohexane core by a highly diastereoselective Lewis acid-catalyzed carbonyl-ene reaction. In the overall process, four contiguous stereogenic centers including two quaternary stereogenic centers were installed.

Nucleo-Palladation-Triggering Alkene Functionalization: A Route to γ-Lactones.

An unprecedented strategy for the highly effective synthesis of γ-lactones from homoallylic alcohols was achieved by palladium catalysis in one step. The protocol affords aryl, alkyl, and spiro γ-lactones directly from readily available homoallylic alcohols in good yields with excellent functional group tolerance and high chemoselectivity under mild conditions.

B-(3,3-Difluoroallyl)diisopinocampheylborane for the Enantioselective Fluoroallylboration of Aldehydes

The fluoroallylboration of aldehydes with B-(3,3-difluoroallyl)diisopinocampheylborane, which was prepared via the hydroboration of 1,1-difluoroallene, provides chiral 2,2-gem-difluorinated homoallylic alcohols in good yields and 91-97% ee.

Stereoselective synthesis of pseudoglycosides catalyzed by TeCl4 under mild conditions

Catalytic amounts of tellurium(IV) tetrachloride were used to promote the O-glycosylation of 3,4,6-tri-O-acetyl-d-glucal to give the corresponding 2,3-unsaturated-O-glycosides. With simple alcohols, the desired compounds were obtained in good yields and excellent anomeric selectivity in a short reaction time using only 2mol% of the catalyst. The application of the method in the synthesis of a small set of glycopyranosides with rigid or flexible linkers gave the corresponding α anomers as products in good yields. Further applications of some of the synthesized compounds in allylation reaction of aldehydes gave the corresponding homoallylic alcohols in good yields.

Stereoselective synthesis of pseudoglycosides catalyzed by TeCl4 under mild conditions

Catalytic amounts of tellurium(IV) tetrachloride were used to promote the O-glycosylation of 3,4,6-tri-O-acetyl-d-glucal to give the corresponding 2,3-unsaturated-O-glycosides. With simple alcohols, the desired compounds were obtained in good yields and excellent anomeric selectivity in a short reaction time using only 2mol% of the catalyst. The application of the method in the synthesis of a small set of glycopyranosides with rigid or flexible linkers gave the corresponding α anomers as products in good yields. Further applications of some of the synthesized compounds in allylation reaction of aldehydes gave the corresponding homoallylic alcohols in good yields.

ChemInform Abstract: Rhodium‐Catalyzed Reductive Allylation of Conjugated Aldehydes with Allyl Acetate

Abstractfurnishing homoallylic alcohols in good yields

ChemInform Abstract: Optical Resolution of 2- and 3-Hydroxyalkyltriphenylphosphonium Salts. Stereoselective Synthesis of Enantiomerically Pure (E)- and (Z)- Homoallylic Alcohols.

Optically active 2- and 3-hydroxyalkyltriphenylphosphonium salts were prepared by the optical resolution of their 2,3-di-O-benzoyltartrates. The reaction of these salts with butyllithium afforded the corresponding ylides, which reacted with aldehydes to give optically active (E)-homoallylic alcohols in good yields. 3-Hydroxyalkyltriphenylphosphonium salts were converted into the corresponding diphenylphosphine oxides by the reaction with aq NaOH, which reacted with sodium hydride followed by the addition of benzaldehyde to afford optically active (Z)-homoallylic alcohols.

Pd(II)-catalyzed and diethylzinc-mediated asymmetric umpolung allylation of aldehydes in the presence of chiral phosphine-Schiff base type ligands

Chiral phosphine-Schiff base type ligand L3 prepared from ( R)-(−)-2-(diphenylphosphino)-1,1′-binaphthyl-2′-amine was found to be a fairly effective chiral ligand for the Pd(II)-catalyzed and diethylzinc-mediated enantioselective umpolung allylation of aldehydes to give homoallylic alcohols in good yields, moderate enantioselectivities and high syn diastereoselectivities.

Mg(NTf2)2·xH2O: An Efficient Catalyst for the Synthesis of Homoallylic Alcohols in Water

An efficient method has been developed for the allylation of aldehydes with allytributylstannane in the presence of a catalytic amount of Mg(NTf2)2·xH2O at room temperature in water to afford the corresponding homoallylic alcohols in good yields.

Chiral pyridine N-oxides derived from monoterpenes as organocatalysts for stereoselective reactions with allyltrichlorosilane and tetrachlorosilane

The synthesis of enantiomerically pure C 2-symmetric dipyridylmethane ligands and related N, N′-dioxides is reported. A procedure for the synthesis of a few new enantiomerically pure C 2-symmetric pyridine N-oxides and the preparation of four pyridine N-oxides with oxygen and nitrogen atoms as further coordinating elements in the heterocycle framework is described. All compounds were prepared from naturally occurring monoterpenes. These new compounds were assessed as organocatalysts in two different reactions, namely the allylation of aldehydes with allyltrichlorosilane that afforded homoallylic alcohols in good yields and up to 85% ee and the stilbene oxide opening by the addition of tetrachlorosilane that gave chlorohydrin in quantitative yield and up to 70% ee.

Nano‐Aluminum Powder Mediated Allylation of Carbonyl Compounds in Aqueous Media

AbstractA new and effective Barbier‐Grignard allylation of aldehydes or ketones has been carried out with nano‐aluminum powder in aqueous 0.1 mol·L−1 NH4Cl (aq.) under an atmosphere of nitrogen. Aromatic carbonyl compounds gave homoallylic alcohols in good yields. The effectiveness of reaction was strongly influenced by the steric environment surrounding the carbonyl group. Aliphatic carbonyl compounds proceeded in low yields. The dominant stereoisomer was an erythro‐isomer when an ortho‐hydroxyl carbonyl compound was reacted under such a reaction condition.

Simple, One‐Pot Procedure for the Generation of Homoallylic Alcohols from Barbier‐Type Allylation of Gem‐diacetates in the Presence of β‐Cyclodextrin in Water

A novel and highly efficient allylation of gem‐diacetates using allylbromide has been developed in aqueous medium catalyzed by β‐cyclodextrin in the presence of Zn‐mediated Barbier‐type allylation to afford the corresponding homoallylic alcohols in good yields. The β‐cyclodextrin can be recovered and reused for a number of runs without significant loss of activity.

Novel Approach to Multifunctionalized Homoallylic Alcohols via Regioselective Ring Opening of Aryl Oxiranes with 3-Iodo Allenoates

[reaction: see text] 3-Iodo allenoates were generated in situ and utilized, for the first time, in the ring opening of oxiranes in a regioselective fashion. This simple one-pot three-component reaction protocol provides easy access to highly functionalized homoallylic alcohols in good yields and moderate to very good (Z/E) selectivity. The two functional groups (ester and halogen) can be further subjected to many synthetic transformations.

β‐Cyclodextrin Promoted Allylation of Aldehydes with Allyltributyltin under Supramolecular Catalysis in Water.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Barbier‐Type Reaction Mediated with Tin Nano‐Particles in Water.

AbstractFor Abstract see ChemInform Abstract in Full Text.

β-Cyclodextrin promoted allylation of aldehydes with allyltributyltin under supramolecular catalysis in water

A novel and highly efficient allylation of aldehydes using allyltributyltin has been developed in aqueous medium catalyzed by β-cyclodextrin in the presence of HCl without any metal catalysts to afford the corresponding homoallylic alcohols in good yields. The β-cyclodextrin can be recovered and reused for a number of runs without significant loss of activity.

Barbier-type reaction mediated with tin nano-particles in water

Tin nano-particles are employed in the Barbier-type allylation reaction of carbonyl compounds in water to afford the corresponding homoallylic alcohols in good yields. The in situ generated allylation intermediates, allyltin(II) bromide and diallyltin dibromide, have been directly observed by using 1H NMR. A mechanism is proposed based on this observation.

Catalytic Asymmetric Allylation of Ketones and a Tandem Asymmetric Allylation/Diastereoselective Epoxidation of Cyclic Enones.

AbstractFor Abstract see ChemInform Abstract in Full Text.