Β-amino Ketones Research Articles

Asymmetric Mannich‐Type Reaction of a Chiral N‐(tert‐Butylsulfinyl) Ketimine with Imines: Application to the Synthesis of Chiral 1,3‐Diamines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Synthesis of β‐Amino Ketones by Iridium(III)‐Catalyzed Direct‐Mannich Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Direct-type catalytic three-component Mannich reaction in aqueous media

Bismuth triflate catalyzed direct-type Mannich reaction of cyclohexanone, aromatic aldehyde, and aromatic amine proceeded smoothly in water to afford the corresponding β-amino ketone with very good yield and moderate to good anti selectivity.

Synthesis of β-amino carbonyl compounds via a Zn(OTf) 2-catalyzed cascade reaction of anilines with aromatic aldehydes and carbonyl compounds

A Zn(OTf) 2-catalyzed cascade reaction of anilines with aromatic aldehydes and carbonyl compounds was described. This one-pot three-component reaction afforded the corresponding β-amino carbonyl compounds, β-amino esters, and β-amino ketones in good to excellent yields. The reaction was also applied for the liquid-phase synthesis of β-amino carbonyl compound library using PEG as a support.

ZrCl4-catalyzed aza-Michael addition of carbamates to enones: Synthesis of Cbz-protected β-amino ketones

The reaction of α,β-unsaturated ketones with benzyl carbamate and 2-oxazolidinone was effectively promoted by a catalytic amount of zirconium (IV) chloride to produce the corresponding β-amino ketones.

α‐Methylene‐β‐amino Ketone Derivatives from β‐Ketoallylsilanes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Remarkable Effects of Additives to Facilitate Aza-Mannich Type Reaction: A Rapid Access to β-Amino Ketone O-Alkyl Oximes

Aza-Mannich-type reaction proceeded between imines and the aza-enolates formed from α-iodomethyl ketone O-alkyl oximes with titanium tetraiodide to give β-amino ketone O-alkyl oximes in good to excellent yields. Remarkable effects of added silica gel or molecular sieves (4 A) were observed to promote the addition reactions.

Direct synthesis of Cbz-protected β-amino ketones by iodine-catalyzed three-component condensation of aldehydes, ketones and benzyl carbamate

Iodine has been found to be very effective catalyst for a Mannich reaction between an aryl aldehyde, an aryl ketone and benzyl carbamate, even though this is a less reactive amine, to produce Cbz-protected β-aryl β-amino carbonyl compounds in high yields.

Synthesis of β-Amino Ketones by Iridium(III)-catalyzed Direct-Mannich Reaction

Abstract The direct-Mannich reaction of ketones 1, aldehydes 2, and anilines 3 was studied using catalytic amount of transition-metal complexes. The trivalent iridium complex, [IrCl2(H)(cod)]2, catalyzed the direct-Mannich reaction effectively to give various β-amino kenotes in good yields under mild conditions.

Unexpected Ring-Opening Reactions of Aziridines with Aldehydes Catalyzed by Nucleophilic Carbenes under Aerobic Conditions

[reaction: see text] The chemoselective ring opening of N-tosyl aziridines with aldehydes catalyzed by an N-heterocyclic carbene was investigated under aerobic conditions. Unexpected carboxylates of 1,2-amino alcohols from the corresponding aldehydes, rather than the acyl anion ring-opened beta-amino ketones, were exclusively obtained. A plausible mechanism for this unprecedented carbene-mediated reaction was also proposed.

Convenient Asymmetric Synthesis of β-Trifluoromethyl-β-amino Acid, β-Amino Ketones, and γ-Amino Alcohols via Reformatsky and Mannich-Type Reactions from 2-Trifluoromethyl-1,3-oxazolidines

The stereoselective syntheses of beta-trifluoromethyl-beta-amino ester, beta lactams, and beta-amino ketones starting from an oxazolidine derived from trifluoroacetaldehyde hemiacetal and (R)-phenylglycinol are reported. The Mannich-type reaction involving a chiral fluorinated iminium ion occurred in a good yield and with a higher stereoselectivity (dr up to 96:4) than that of the Reformatsky-type reaction. This straightforward strategy was applied to the short syntheses of (R)-3-amino-4,4,4-trifluorobutanoic acid, a series of novel enantiopure unprotected fluorinated beta-amino ketones, and their corresponding gamma-amino alcohols.

Synthesis of β-Amino Ketones and β-Amino Alcohols

Reductive ring opening of 3,5-di­substituted 2,3-dihydroisoxazoles using sodium borohydride in acetic acid followed by zinc in acetic acid gave the corresponding syn-β-amino alcohols with good yields and diastereoselectivity. The reaction can be performed in one pot. Treatment of the 3,5-disubstituted 2,3-dihydroisoxazoles with zinc and acetic acid gave the β-amino ketone in good to excellent yield. Lower yields were obtained when R1 = Ph, due to the formation of an competing α,β-unsatured ketone. An anomalous result was observed with R2 = Ph: treatment of the 2,3-dihydroisoxazole with zinc in acetic acid produced the anti-β-amino alcohol rather than the expected β-amino ketone.

Aminoboranes as new iminium ion generators in amination reactions

Abstract The utilization of aminoborane derivatives in amination reactions such as Strecker-type aminative cyanation, Mannich-type reaction, and reductive amination is described. Bis(dialkylamino)cyanoboranes and bis(dialkylamino)boron enolates underwent the concurrent transfer of the amino group and either the cyano or the enoxy group from the boron to carbonyl carbon atom in their reaction with aldehydes, leading to the formation of α-amino nitriles and β-amino ketones, respectively. Bis(dialkylamino)borane derivatives that lack the additional nucleophilic groups on the boron atoms were found to serve as effective generators of iminium ions from aldehydes. In the presence of these aminoboranes, reactions of aldehydes with ketene silyl acetals or silyl enol ethers take place, giving Mannich-type products, i.e., β-amino esters and ketones, selectively. Using diisopropylamino-substituted boron compounds, which are designed as "universal" iminium ion generators, reactions of free sec-amines, aldehydes, and ketene silyl acetals proceed efficiently, giving β-amino esters in which the amino groups are derived exclusively from the free amines. The use of the universal iminium ion generator is also effective for reductive amination of aldehydes, in which NaBH4 is used as a hydride donor.

Imino‐ene Reaction of N‐Tosyl Arylaldimines with α‐Methylstyrene: Application in the Synthesis of Important Amines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis, characterization and activity study of SO 42−/Ce xZr 1− xO 2 solid superacid catalyst

Sulfated Ce x Zr 1− x O 2 catalyst was found to exhibit solid super-acidity and good catalytic activity for synthesis of β-amino ketones by a three-component Mannich type reaction in the liquid phase under solvent free conditions at ambient temperature. To make the sulfated Ce x Zr 1− x O 2 catalyst, Ce-Zr hydroxide gel was prepared by a coprecipitation method and SO 4 2− ions were deposited by treating the gel with sulfuric acid and calcined at 923 K. Surface and bulk properties of the Ce x Zr 1− x O 2 and SO 4 2−/Ce x Zr 1− x O 2 samples were investigated by means of X-ray powder diffraction, thermogravimetry, ammonia-TPD, Raman spectroscopy and BET surface area methods. Characterization results indicate that impregnated SO 4 2− ions strongly influence the physicochemical characteristics of the Ce x Zr 1− x O 2 solid solution. Powder XRD profiles reveal the presence of cubic Ce 0.5Zr 0.5O 2 in the case of unpromoted sample and tetragonal Ce 0.16Zr 0.84O 2 phase along with zirconium sulfate compounds in the case of SO 4 2− promoted sample. In particular, the XRD and Raman results suggest a selective interaction of the sulfate ions with zirconia portion of the Ce x Zr 1− x O 2 solid solution leading to the formation of zirconium sulfate compounds. The NH 3-TPD profiles indicate significant changes in the distribution of acid sites on the Ce x Zr 1− x O 2 upon sulfation. The SO 4 2−/Ce x Zr 1− x O 2 sample exhibits strong as well as super-acidic sites.

Molecular Iodine Catalyzed Imine Activation for Three‐Component Nucleophilic Addition Reactions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

HCl‐Catalyzed Stereoselective Mannich Reaction in H2O—SDS System.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Imino-ene reaction of N-tosyl arylaldimines with α-methylstyrene: application in the synthesis of important amines

Copper(II) or tin(II) trifluoromethanesulfonate in combination with TMSCl effectively activates a C–H bond for the imino-ene reaction of N-tosylarylaldimines with α-methylstyrene. A wide variety of N-tosylarylaldimines were used to give homoallylamines in good to excellent yields under mild conditions. The imino-ene adduct was converted into a β-amino ketone. The synthesis of a 2,4-substituted pyrrolidine and a piperidine was also achieved from the imino-ene product via a Mitsunobu reaction and a Grubbs cyclization, respectively.

Asymmetric Synthesis of α-Substituted β-Amino Ketones from Sulfinimines (N-Sulfinyl Imines). Synthesis of the Indolizidine Alkaloid (−)-223A

Of the possible four stereoisomers, addition of the lithium enolate of 4-heptanone to sulfinimines resulted in only the syn- and anti-alpha-substituted beta-amino ketones. The formation of the major syn-beta-amino ketone was rationalized in terms of addition of the E-enolate to the C-N double bond of the sulfinimine via a six-member chelated chairlike transition state. The enolates of 4-heptanone were generated using LiHMDS in THF where a 1:2.5 E:Z enolate ratio was noted. In diethyl ether the E:Z ratio was 15:1 in favor of the E-enolate and explained in terms of Ireland's transition state model. Here increased steric interactions between the ethyl group and the carbonyl-LiN(TMS)(2) moiety destabilize the transition state leading to the Z-enolate in the poorly coordinating diethyl ether solvent. This new synthesis of syn-alpha-substituted-beta-amino ketones was applied to the concise enantioselective total synthesis of indolizidine (-)-223A, a 5,6,8-trisubstituted alkaloid isolated from the skin of the dendrobatide frog.

Highly Enantioselective Conjugate Additions to α,β‐Unsaturated Ketones Catalyzed by a (Salen)Al Complex.

AbstractFor Abstract see ChemInform Abstract in Full Text.