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A simple two-step procedure converts 2-substituted N-acyl-2,3-dihydro-4-pyridones to 2,4-disubstituted N-acyl-5,6-dihydro-2-pyridones.

Intramolecular Heck reactions of N-acyl-2,3-dihydro-4-pyridones provide polycyclic heterocycles with high regio- and stereoselectivity.

The C-5 position of N-Acyl-2-alkyl-2,3-dihydro-4-pyridones can be substituted by halogenation followed by a cross-coupling or carbonylation reaction.

The oxidation of silyl enol ethers 2 with palladium(II) acetate is a convenient method for the preparation of synthetically useful 2,6-disubstituted 2,3-dihydro-4-pyridones 3.

Grignard addition to a chiral 1-acyl-4-methoxypyridinium salt provides synthetically useful 2-alkyl(aryl)-2,3-dihydro-4-pyridones in high diastereomeric excess

The full details are given of a study on the conversion of dihydropyridones of the type 3 to 4-chloro-1,2-dihydropyridines 4 using a Vilsmeier reagent. The use of 1 equiv of Vilsmeier reagent under mild conditions (CICHCCl 2 , rt) transformed several racemic N-acyl-2,3-dihydro-4-pyridones 3 to dihydropyridines 4 in very good to excellent yields (83-96%). A C-3 methyl group can be tolerated as was demonstrated in the preparation of 4-chloro-3-methyl-1,2-dihydropyridine 7 from dihydropyridone 6 in 90% yield. The utility of this conversion was demonstrated in the synthesis of the piperidine alkaloid, (-)-coniine. The synthesis of (-)-coniine was completed in five steps from 4-methoxy-3(triisopropylsilyl)pyridine in 54% overall yield. When 2,3-dihydro-4-pyridones are treated with excess Vilsmeier reagent, good yields of 4-chloro-3-formyl-1,2-dihydropyridines result. These heterocycles are useful intermediates for alkaloid preparation, as shown by two syntheses of the quinolizidines alkaloid, (±)-lupinine, carried out in three and five steps, respectively

The full details are given of a study on the conversion of dihydropyridones of the type 3 to 4-chloro-1,2-dihydropyridines 4 using a Vilsmeier reagent. The use of 1 equiv of Vilsmeier reagent under mild conditions (CICHCCl 2 , rt) transformed several racemic N-acyl-2,3-dihydro-4-pyridones 3 to dihydropyridines 4 in very good to excellent yields (83-96%). A C-3 methyl group can be tolerated as was demonstrated in the preparation of 4-chloro-3-methyl-1,2-dihydropyridine 7 from dihydropyridone 6 in 90% yield. The utility of this conversion was demonstrated in the synthesis of the piperidine alkaloid, (-)-coniine. The synthesis of (-)-coniine was completed in five steps from 4-methoxy-3(triisopropylsilyl)pyridine in 54% overall yield. When 2,3-dihydro-4-pyridones are treated with excess Vilsmeier reagent, good yields of 4-chloro-3-formyl-1,2-dihydropyridines result. These heterocycles are useful intermediates for alkaloid preparation, as shown by two syntheses of the quinolizidines alkaloid, (±)-lupinine, carried out in three and five steps, respectively

Grignard addition to a chiral 1-acyl-4-methoxypyridinium salt provides synthetically useful 2-alkyl(aryl)-2,3-dihydro-4-pyridones in high diastereomeric excess

The crystal structure and the relative stereochemistry of the four asymmetric centers of an unusual C-4a hydroxylated decahydroquinolone, phenyl 1,2 alpha,3,4,-4a alpha,5 beta,6,7,8,8a alpha-decahydro-4a-hydroxy-4-oxo-2-propyl-5-vinylquinoline-1 -carboxylate, C21H27NO4, are reported. The H and OH groups at the ring juncture are cis to each other as are the two H atoms alpha to the N atom. The vinyl and OH groups are also cis to each other. The N atom is sp2 hybridized.

The oxidation of silyl enol ethers 2 with palladium(II) acetate is a convenient method for the preparation of synthetically useful 2,6-disubstituted 2,3-dihydro-4-pyridones 3.

The C-5 position of N-Acyl-2-alkyl-2,3-dihydro-4-pyridones can be substituted by halogenation followed by a cross-coupling or carbonylation reaction.

Intramolecular Heck reactions of N-acyl-2,3-dihydro-4-pyridones provide polycyclic heterocycles with high regio- and stereoselectivity.

A simple two-step procedure converts 2-substituted N-acyl-2,3-dihydro-4-pyridones to 2,4-disubstituted N-acyl-5,6-dihydro-2-pyridones.

[formula: see text] Concise asymmetric syntheses of several benzomorphan derivatives have been accomplished using enantiopure 2,3-dihydro-4-pyridones as chiral building blocks.

N-Acyl-2,3-dihydro-4-pyridones are converted to 1-acyl-4-chloro-1,2-dihydropyridines in one step using one equivalent of Vilsmeier reagent. This conversion was utilized in an asymmetric synthesis of (−)-coniine.

Pyridine-derived triflating reagents: N-(2-pyridyl)-triflimide and N-(5-chloro-2-pyridyl)triflimide product: N-(2-pyridyl)triflimide product: N-(5-chloro-2-pyridyl)triflimide Keywords: sulfonation, N-sulfonation; sulfonation, N-sulfonation

The crystal structure and the relative stereochemistry of the four asymmetric centers of an unusual C-4a hydroxylated decahydroquinolone, phenyl 1,2 alpha,3,4,-4a alpha,5 beta,6,7,8,8a alpha-decahydro-4a-hydroxy-4-oxo-2-propyl-5-vinylquinoline-1 -carboxylate, C21H27NO4, are reported. The H and OH groups at the ring juncture are cis to each other as are the two H atoms alpha to the N atom. The vinyl and OH groups are also cis to each other. The N atom is sp2 hybridized.

[–] C5H13LiN2 (MW 108.14) InChI = 1S/C5H13N2.Li/c1-6-4-5-7(2)3;/h4-5H2,1-3H3;/q-1;+1 InChIKey = WQCOCAOFFMHNAF-UHFFFAOYSA-N (reagent for the in situ formation of α-amino alkoxides, which are effective directing groups for ortho lithiation1) Alternate Name: LTMDA. Preparative Methods: prepared in situ by adding n-BuLi to N,N,N′-trimethylethylenediamine in anhydrous solvents. Handling, Storage, and Precautions: highly flammable; should be kept under a nitrogen or argon atmosphere. Handle in a fume hood.

[105563-31-3] C5H11LiN2 (MW 106.12) InChI = 1S/C5H11N2.Li/c1-7-4-2-6-3-5-7;/h2-5H2,1H3;/q-1;+1 InChIKey = QVLUVDRMLBBAOV-UHFFFAOYSA-N (in situ protection of aryl aldehydes via α-amino alkoxide formation; α-amino alkoxides can direct or block ortho-lithiation1) Alternate Names: LNMP. Preparative Method: prepared in situ by adding n-Butyllithium to N-methylpiperazine in anhydrous solvents. Handling, Storage, and Precautions: highly flammable; should be kept under a nitrogen or argon atmosphere.

[68-12-2] C3H7NO (MW 73.11) InChI = 1S/C3H7NO/c1-4(2)3-5/h3H,1-2H3 InChIKey = ZMXDDKWLCZADIW-UHFFFAOYSA-N (formylating agent for certain organometallics2-5; used in combination with POCl3 or acid halides to form the reactive Vilsmeier reagent8, 9) Alternate Name: DMF. Physical Data: mp −61 °C; bp 153 °C; d 0.944 g cm−3; fp 57 °C. Solubility: miscible with water and most organic solvents. Form Supplied in: clear liquid; both d7 and 13C forms are available commercially; widely available. Purification: decomposes slightly at its normal boiling point to give small quantities of of dimethylamine and carbon monoxide. The decomposition is catalyzed by acidic or basic materials so that even at rt DMF is appreciably decomposed if allowed to stand for several hours with solid KOH, NaOH, or CaH2. Drying agents suitable for DMF are CaSO4, MgSO4, silica gel, and 4A molecular sieves. After drying, distillation under reduced pressure will give reasonably dry DMF adequate for most laboratory purposes. Anhydrous DMF can be prepared by using certain desiccants.1b Handling, Storage, and Precautions: anhydrous DMF should be stored under a nitrogen atmosphere in sure seal bottles or metallic cylinders; vapors are harmful, irritating to skin, eyes, and mucous membranes; it is suspected to be a carcinogen; use in a fume hood.

[67242-59-5] C7H8N2O (MW 136.17) InChI = 1S/C7H8N2O/c1-9(6-10)7-4-2-3-5-8-7/h2-6H,1H3 InChIKey = DIRVEOCOAHGVJV-UHFFFAOYSA-N (formylating reagent for Grignard reagents1 and certain organolithiums;6 sequential addition of two Grignard reagents can provide unsymmetrical secondary alcohols3) Alternate Name: 2-(N-formyl-N-methyl)aminopyridine. Physical Data: bp 71–72 °C/0.05 mmHg; d 1.137 g cm−3. Form Supplied in: colorless liquid; commercially available. Analysis of Reagent Purity: IR, NMR. Handling, Storage, and Precautions: moisture sensitive; irritant; should be kept under argon or nitrogen.

[formula: see text] Concise asymmetric syntheses of several benzomorphan derivatives have been accomplished using enantiopure 2,3-dihydro-4-pyridones as chiral building blocks.

The 4-methoxypyridinium and oxycarbonyl moieties are coplanar and approximately parallel to the phenyl ring. The latter is involved in a number of short intramolecular interactions with the pyridinium and the oxycarbonyl atoms. Crystal packing is characterized by the presence of hydrophobic and hydrophilic channels, the former consisting of phenylmenthyl groups and the latter of pyridinium and SbCl 6 - ions

3,4-Dihydro-2H-pyrrole-l-oxides la-e react with Chlorosulfonyl isocyanate (CSI), to give the 2H-pyrroles 2a-e. 3,4-Dihydro-2,2,4,4-tetramethyl-2H-pyrrole-1-oxide If on treatment with CSI furnished ...

Reaction of chlorosulfonyl isocyanate (CSI) with nitrones (derived from cyclic conjugated ketones), 1 - 7 and 3,4-dihydro-2H-pyrrole-1-oxides, 15a - f ,-has been studied. Nitrones, 1 - 7 , react with CSI to form the enamidea, 8 , 10 - 14 , and the cyclil-amide, 9 , in yields ranging from 33 to 72 %. However, the 5,4-dihydro-2H-pyrrole-1-oxides, 15a - e , on reaction with CSI gave the 2H-pyrr-oles, 16a - e , in good yields. The 3,4-dihydro-2H-pyrrole-1-oxide, 15f , under similar experimental conditions gave the pyrrolidone, 17f , in 40% yield. Plausible mechanisms for the above mentioned rearrangement and conversions have been proposed with experimental evidences.

Abstract-Benzopinacolones, 1a-c, reacted with chlorosulfonyl isocyanate (CSI) at 130[ddot]C to yield the benzopinacolone-2′ -sulfonamides, 4a-c. Similarly benzophenones, 5a-d, reacted with CSI to give the benzoisothiazole-1, 1-dioxides, 7a-d.

Reaction of chlorosulfonyl isocyanate (CSI) with nitrones 1 a-n and 5 a,b has been studied. α, α, N-Triaryl nitrones 1 a-n react with CSI to form the N,N-diaryl arylamides 3 a-n and 4 i-n in good yields. In the case of α-H, α, N-diaryl nitrones 5 a,b however, two compounds viz., the rearranged product 11 a,b and the 1,4-dihydro tetrazines 10 a,b are formed. The effect of substituents on the rearrangement has been studied. It is found that the nature of the substituent has got a profound effect on the rearrangement. We have also noted that the rearrangement is independent of the syn or anti configurations of the nitrones.

1,2-Diols, 1a-e, upon reaction with chloro-sulfonyl isocyanate (CSI) gave the ketones, 3a-e Under similar experimental conditions, 1,2-diols, 1f-k, gave carbonyl compounds, 3f-k, carbonates, 6f-k, carboxamides, 7h, i, and the epoxide, 5i.

Reaction of chlorosulfonyl isocyanate (CSI) with nitrones (derived from cyclic conjugated ketones), 1 - 7 and 3,4-dihydro-2H-pyrrole-1-oxides, 15a - f ,-has been studied. Nitrones, 1 - 7 , react with CSI to form the enamidea, 8 , 10 - 14 , and the cyclil-amide, 9 , in yields ranging from 33 to 72 %. However, the 5,4-dihydro-2H-pyrrole-1-oxides, 15a - e , on reaction with CSI gave the 2H-pyrr-oles, 16a - e , in good yields. The 3,4-dihydro-2H-pyrrole-1-oxide, 15f , under similar experimental conditions gave the pyrrolidone, 17f , in 40% yield. Plausible mechanisms for the above mentioned rearrangement and conversions have been proposed with experimental evidences.

1,2-Diols, 1a-e, upon reaction with chloro-sulfonyl isocyanate (CSI) gave the ketones, 3a-e Under similar experimental conditions, 1,2-diols, 1f-k, gave carbonyl compounds, 3f-k, carbonates, 6f-k, carboxamides, 7h, i, and the epoxide, 5i.

The addition of allyltributylstannane (1) and but-2-enyltributylstannane (2) to aldehydes (3) in presence of cobalt(II) chloride proceeds in a regioreversed manner as indicated by the exclusive formation of α-adducts (5) from (2) in good yields.