Β-keto Sulfoxide Research Articles

Transition metal-free and solvent-free calcium carbide promotes the formation of β-keto sulfoxide from acyl chloride and DMSO

A transition metal-free, solvent-free, cheap and readily available calcium carbide promoted one-pot reaction of acid chloride with dimethyl sulfoxide produced β-keto sulfoxide directly.

Stereoselective synthesis of the C15–C26 fragment of the antitumor agent (−)-dictyostatin

The synthesis of the C15-C26 fragment of (-)-dictyostatin is reported in 10 steps and 28% overall yield. The key steps are the two stereoselective sulfoxide-directed processes: a Reformatsky-type reaction and a β-keto sulfoxide reduction.

ChemInform Abstract: Highly Stereoselective Double Michael Cyclization of 1-Phenylsulfinyl and Sulfonyl Analogues of the Nazarov Reagent.

The base-catalyzed double Michael addition of the β-keto sulfoxide 5 with 2-carbomethoxy-2-cyclohexenone (1) proceeds, after elimination of the sulfoxide moiety during chromatography on silica, to give the dehydrodecalin adduct 6 with high stereoselectivity.

A formal synthesis of (+)-(S)-kurasoin B

A new diastereoselective synthesis of (S)-1-[(S)-oxiran-2-yl]-2-phenylethanone (10), a key intermediate in the synthesis of kurasoin B (2), has been accomplished in seven steps in an overall yield of 32%. The key synthetic step in the process is the diastereoselective reduction of the β-keto sulfoxide 6 derived from (S)-phenyllactic acid.

Formal Synthesis of (-)-Frontalin through Diastereoselective Hydrocyanation of a β-Keto Sulfoxide

The diastereoselective synthesis of (S)-4-(2,2,4-trimethyl-1,3-dioxolan-4-yl)butan-1-ol (9), an intermediate in the asymmetric synthesis of the pine beetle pheromone (-)-frontalin [(1S,5R)-1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane] (1), has been accomplished starting from the β-keto sulfoxide 2, derived from glutaric anhydride. The key step of the synthetic sequence is the diastereoselective hydrocyanation of 2 by diethylaluminum cyanide.

An Asymmetric Biaryl Suzuki Cross‐Coupling Reaction: Stereogenic Benzylic Carbinols as Chiral Auxiliaries.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A short enantiodivergent synthesis of d- erythro and l- threo sphingosine

A new, short (6 steps) and efficient enantiodivergent route to both D- erythro and L threo-sphingosine I and II is disclosed. The high diastereoselection (100% de) reached in the creation of the C-3 stereocenter relies on the use of a sulfoxide as chiral controlling agent in the reduction of the common precursor β-keto sulfoxide 3. The desired E-alkene of sphingosines has been constructed by the Schlosser modification of the Wittig reaction between the aldehyde 8 and the phosphonium salt 9. The reported methodology can easily be extended to the synthesis of a large number of optically pure syn and anti amino alcohols starting from commercially available amino acids.

An Easy and Efficient Method for Cleavage of Carbon-Nitrogen Double Bonds Under Non-Aqueous and Neutral Conditions

1-Benzyl-4-aza-1-azoniabicyclo[2.2.2]octane periodate (BAABCP) (1), readily prepared as an orange solid from commercially available DABCO (1,4-diazabicyclo [2.2.2]octane, performs oxidation in anhydrous conditions. Under these conditions, the reagent converts phenylhydrazones, p-phenylhydrazones, semicarbazones, and β-keto sulfoxide hydrazones to the corresponding carbonyl compounds and β-keto sulfoxides respectively, the yields and enantioselectivity are excellent.

Synthesis of enantiomerically pure juvenile hormone II

An efficient preparative method for the enantiomerically pure juvenile hormone II has been developed by applying the diastereoselective alkylation and carbonyl reduction of an optically pure β-keto sulfoxide as the key steps.

Asymmetric synthesis of the C-3/C-9 fragment of (−) aspicilin

The optically active C-3/C-9 fragment of (−) aspicilin is synthesized by reduction of an allylic β-keto sulfoxide followed by hydroxylation of the double bond.

A New Synthesis of β-Keto Sulfoxides from Chloromethyl Aryl Sulfoxide and Aldehydes

Abstract Addition of the carbanion of chloromethyl aryl sulfoxide to aldehyde gave the adduct, which was treated with three-equivalents of lithium diisopropylamide (LDA) to afford β-keto sulfoxide in high overall yield.

Highly stereoselective double michael cyclization of 1-phenylsulfinyl and sulfonyl analogues of the nazarov reagent

The base-catalyzed double Michael addition of the β-keto sulfoxide 5 with 2-carbomethoxy-2-cyclohexenone ( 1) proceeds, after elimination of the sulfoxide moiety during chromatography on silica, to give the dehydrodecalin adduct 6 with high stereoselectivity.

The Conversion of Ethyl Dienol Ether and Dienyl Pivalate Derivatives of Hagemanns Ester Into Bicyclic Enones

The cyclization of compounds obtained from ethyl dienol ether and dienyl pivalate derivatives of Hagemann's ester has been examined. The carbanions of methyl phenyl sulfone and methyl phenyl sulfoxide react with the methylated dienol ether (4) to give the β-keto sulfone (8) and sulfoxide (9), the former of which was converted into the oxabicyclo[4.3.0]non-1-en-3-one (16). The iodide (17) with potassium t-butoxide in t-butyl alcohol gave the octahydronaphthalenone (18). With lithium ethoxide in tetrahydrofuran the octahydronaphthalenedione (22) was obtained from the dienyl pivalate (24). Both reactions involve the generation and intramolecular cyclization of a dienolate produced by cleavage of the pivaloyl group in each of (17) and (24). The scope and limitations of these reactions are briefly discussed.

Synthesis and 13C nuclear magnetic resonance assignments of cannithrene 1: a cannabis constituent

Two synthetic approaches to cannithrene 1 (1) have been explored. One-pot annelation of 6,8-dimethoxytetralone by first forming a β-keto sulfoxide, then addition of methyl vinyl ketone, gave, unexpectedly, after elimination of the sulfoxide, the naphthol (10). The successful route to cannithrene 1 (1) involved regiospecific demethylation of 6,8-dimethoxytetralone, then its conversion to enone 16. Pyridinium bromide perbromide provided the necessary aromatization to give cannithrene 1 (1) after deprotection by hydrogenolysis. The 13C nmr assignments of 1 were made.

α-Fluorination of β-keto sulfoxides

We have developed an efficient new procedure for α-fluorination of β-keto sulfoxide enolate anions which are generated in situ via nucleophilic addition reactions to cyclopentenone sulfoxide 7. Perchloryl fluoride is used as the fluorinating agent. Characterization of the product α-fluoro β-keto sulfoxides includes 19F NMR spectroscopy.

ChemInform Abstract: REACTIONS AND SYNTHETIC APPLICATIONS OF β‐KETO SULFOXIDES. X. SYNTHESIS OF ELLIPTICINE ANALOGS MODIFIED AT THE 5‐POSITION

AbstractDas aus dem Indolylbuttersäureester (I) mit Methylthiodimethylsulfoxid (II) leicht zugängliche β‐Ketosulfoxid (III) cyclisiert säurekatalysiert zum Dithioacetal (IV), das mit dem Lithioacetat (V) über den Hydroxyester (VI) zum Carbazol (VII) reagiert.

Reactions and synthetic applications of .BETA.-keto sulfoxides. X. Synthesis of ellipticine analogs modified at the 5-position.

A β-keto sulfoxide (12) derived from ethyl indolebutyrate (11) and methyl methylthiomethyl sulfoxide (MMTS) was cyclized to 4-methyl-1, 1-bismethylthio-2-oxo-1, 2, 3, 4-tetrahydrocarbazole (13) by treatment with p-toluenesulfonic acid (TsOH). Introduction of an acetic ester unit at the carbonyl group with tert-butyllithioacetate gave a key intermediate (14) to all the 5-modified ellipticine analogs. An acid-catalyzed aromatization with acetic acid in xylene gave tert-butyl 4-methyl-1-methylthiocarbazole-2-acetate (15), which was readily converted to 5-methylthioellipticine (7) through a series of usual reactions. The overall yield of 7 from 11 was 25-27%. Desulfurization of 7 with Raney nickel in xylene gave 5-norellipticine (8). The bismethylthio group in 14 was easily hydrolyzed with TsOH in methanol to give a 1-keto compound (21), which was aromatized to a lactone (22), and then converted to 5-methoxyellipticine (9). Hydrolysis of 9 with 47% hydrobromic acid gave 5-hydroxyellipticine (10).

The Nitrosation of β-Keto Sulfoxides

Abstract β-Keto sulfoxides were prepared by the reaction of the esters with the methylsulfinyl carbanion. The nitrosation of the β-keto sulfoxides, RCOCH2SOCH3 (R=C6H5, C6H5CH2CH2, n-C3H7), with sodium nitrite and hydrochloric acid gave the corresponding α-chloro-α-isonitroso ketones, RCOC(=NOH)Cl, in high yields. However, the nitrosation of α-substituted β-keto sulfoxide, RCOCH(R′)SOCH3, in a similar manner afforded the α-isonitroso ketones, RCOC(=NOH)R′. The mechanisms of these reactions were studied.