92694-77-4

Upstream product

• 1024022-48-7 4-(hydroxydiphenylmethyl)-3-hexanone 
• 100-52-7 benzaldehyde 
• 50396-96-8 E-4-hexen-3-one 
• 70280-37-4 4-trimethylsilanyl-hexan-3-one 

Relevant academic research and scientific papers

Generation of rhodium enolates via retro-aldol reaction and its application to regioselective aldol reaction

Retro-aldol reactions of β-hydroxy ketones take place under rhodium catalysis, leading to regioselective formation of the corresponding rhodium enolates. The enolates react with aldehydes in situ to afford the corresponding aldol adducts in high yields.

INTERMOLECULAR ALDOL REACTIONS VIA ALLYLIC O-STANNYL KETYLS

A mild and neutral free radical reaction of an α,β-unsaturated ketone and tributyltin radical produced a resonance-stabilized allylic O-stannyl ketyl intermediate.A tin(IV)enolate, produced by subsequent hydrogen atom transver, was next quenched with various aldehydes to yield an aldol product which was readily eliminated with p-toluenesulfonic acid to afford new α,β-unsaturated ketones with E/Z ratios up to > 100:1.

Stereoselective 1,4-hydroboration of acyclic (E)-α,β-unsaturated ketones with dialkylboranes. Synthesis of (Z)-vinyloxyboranes

Dialkylboranes add to acyclic disubstituted (E)-α,β-unsaturated ketones in a 1,4-fashion affording (Z)-vinyloxyboranes as major or sole products. The stereochemical outcome of the hydroboration reaction is consistent with a concerted pericyclic mechanism. The intermediate vinyloxyboranes can be trapped with aldehydes to give virtually pure syn β-hydroxyketones.

A New Protocol for Regio- and Stereocontrolled Aldol Reactions through the Conjugate Addition of Dialkylboranes to α,β-Unsaturated Ketones

A one-pot, two-step procedure, consisting of the 1,4-addition of dialkylboranes to β-substituted (E)-α,β-unsaturated ketones followed by the reaction of the resulting configurationally pure (Z)-(vinyloxy)boranes with aldehydes, is reported.The overall process corresponds to a regio- and stereocontrolled aldol addition of an unsymmetrical ketone to an aldehyde.A concerted 1,4-addition mechanism accounts for the stereochemical outcome of the hydroboration reaction; cyclic enones do not undergo conjugate addition, while (Z)-β-substituted or β,β-disubstituted α,β-unsaturated ketones still react in a 1,4-fashion, but with a slower rate and a lower degree of chemoselectivity with respect to β-substituted (E)-α,β-unsaturated ketones.In the cases of α,β-disubstituted α,β-unsaturated ketones and (E)-(S-phenylthio)cinnamate, which react with dicyclohexylborane to give a mixture of E and Z enolates, an alternative mechanism is proposed.

A New Approach to (Z)-Vinyloxyboranes via 1,4 Hydroboration of (E)-α,β-Unsaturated Ketones. Synthesis of syn Aldols

(Z)-Vinyloxy boranes are obtained via 1,4-hydroboration of acyclic disubstituted (E)-α,β-unsaturated ketones with dicyclohexylborane or diisopinocampheylborane in tetrahydrofuran, CH2Cl2 or CHCl3 at 20 deg C; treatment of the hydroboration mixture with an aldehyde allows pure syn aldols to be synthesized in good yields, and in excellent enantiomeric excesses, using the latter borane.

Aldol Reactions with α-Trimethylsilyl Ketones. Dual Roles of the Trimethylsilyl Group for Regiospecific Generation of Enolate Equivalents

Aldol reactions of α-trimethylsilyl ketones, R1CH(SiMe3)COCH2R2, with aldehydes or acetals have been examined under Lewis acidic and basic conditions.In the presence of stannic chloride or boron trifluoride etherate, α-trimethylsilyl ketones react with aldehydes or acetals on the carbon bearing the silyl group exclusively to afford the corresponding addition products.On the other hand, lithium diisopropylamide usually deprotonates the opposite carbon atom to generate enolates, R1CH(SiMe3)C(OLi)=CHR2, selectively, which yield another type of aldol product after removal of the silyl group.Thus, two types of aldols can be prepared regioselectively from common α-trimethylsilyl ketones.