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2-Ethyl-tetrahydropyridine

Tetrahydropyridines (THP) include 2-ethyl-tetrahydropyridine (ETHP), 2-acetyl-tetrahydropyridine (ATHP) and 2-acetylpyrroline (APY) (Fig. 11.6). ETHP is present in tautomeric forms, but the second tautomer is minor. ATHP also occurs in two tautomeric forms, of which the distribution is pH dependent. These molecules are uncommon components of wines and are not currently analysed. [Pg.636]

With Af-acyl or Af-sulfonyl hydrazines as nucleophiles, Zincke salts serve as sources of iminopyridinium ylides and ylide precursors.Reaction of the nicotinamide-derived Zincke salt 8 with ethyl hydrazino urethane 42 provided salt 43, while the tosyl hydrazine gave ylide 44 (Scheme 8.4.14). ° Benzoyl hydrazines have also been used in reactions with Zincke salts under similar conditions.Af-amino-1,2,3,6-tetrahydropyridine derivatives such as 47 (Scheme 8.4.15), which showed antiinflammatory activity, are also accessible via this route, with borohydride reduction of the initially formed ylide 46. ... [Pg.361]

Two polymorphic forms of 3- 2-[4-(6-fluorobenzisoxazol-3-yl)-l,2,3,6-tetrahydropyridin-l-yl]ethyl -2-methyl-6,7,8,9-tetrahydro-4//-pyrido[l,2-n] pyrimidin-4-one (137 R = H) were prepared (99MIP1). Racemic 9-hydroxy-2-methyl-3- 2-[4-(6-fluorobenzo[r/ isoxazol-3-yl)-l,2,3,6-tetrahydro-l-pyridyl] ethyl -6,7,8,9-tetrahydro-4//-pyrido[l, 2-n]pyrimidin-4-one was resolved into its (R)- and (5)-isomers (OOMIPIO). [Pg.233]

The intramolecular cycloaddition has proven to be the method of choice for the preparation of steroids. A diastereomeric mixture of 204, prepared from 191 and tosylate 203 has been cleanly converted to dl-estra-1,3,5(10)-trien-17-one (205) in 85% yield (equation 130). A second example of the intramolecular cycloaddition reaction is the formation of the cycloadduct (209), the key intermediate in a synthesis of the As-pidosperma alkaloid aspidospermine, upon heating 208 at 600 °C (equation 131)124. The sulfone 208 can be prepared by reaction of 3-ethyl-3,4,5,6-tetrahydropyridine (206) with the acid chloride 207. [Pg.806]

According to another approach, treatment of A-[2-(indol-3-yl)ethyl]-l,2,5,6-tetrahydropyridine (137), obtained from the corresponding pyridinium salt 136 by borohydride reduction, first with potassium rerf-butoxide, and then with acetic acid, led to ( )-l via key intermediate 135 in 78% yield (102). [Pg.168]

An intermolecular reaction of N-sulfonyl-l,2-propadiene 250 with ethyl vinyl ether leading to tetrahydropyridine 254 was observed [131]. [Pg.639]

Perhaps the strongest evidence in favour of episulfonium ion involvement comes from the isolation of the 4-substituted 1-acetyltetrahydropyridines (137) and (138). Product (138) arises by addition of another molecule of 2-methylpropanethiol to (135). 4-Ethyl-pyridine 1-oxide on reaction with 2-methylpropanethiol, acetic anhydride and TEA yields another type of tetrahydropyridine (137). In this case TEA promotes elimination by abstraction of an ethyl proton, before 2-methylpropanethiol can attack position 6. Conversely, tetrahydropyridines are formed when R=Me, Pr or Pr1, as 2-methylpropanethiol (Scheme 78) is a better nucleophile (at C-6) than TEA is a base (at the 4-substituent). A different tetrahydropyridine (139) is obtained if the starting TV-oxide has a vacant 4-position (Scheme 79). Structural determination of compounds of this type has been greatly facilitated by the availability of 13C NMR (78JHC785). It should be remembered that while 3-substitution... [Pg.231]

Reaction of methyl 4-amino-l-benzyl-l,2,5>6-tetrahydropyridine-3-carboxylate 601 with ethyl isothiocyanoacetate in refluxing pyridine or ethyl iV-[bis(methylthio)methylene]glycinate (BMMA reagent) in AcOH at reflux temperature gave the pyrido[4,3-r7 pyrimidines 603 and 604, respectively, via intermediate 602 (Equation 50) <2001H(55)115>. [Pg.825]

The photochemistry of certain A-substituted heterocycles has also been studied. As part of a continuing investigation of the photolysis of A-nitroso compounds in solution, the conversion of A-nitroso-3-azabicyclo[3.2.2]nonane (65) into the oxime (66) by photolysis in the presence of acid was reported.58 N-Nitrosopyrrolidine is similarly transformed. The mechanism of this reaction is said58 to involve elimination of NOH with the formation of an imine as intermediate, and, in fact, in the photolysis of 2-ethyl-A-nitrosopiperidine (67), the tetrahydropyridine (68) is the major product. This mechanism certainly does not operate in the photolysis of iV-nitroso-2-azacyclo-octanone, which can be rationalized on the basis of an intramolecular hydrogen transfer [Eq. (16)].59 Acyclic iV-nitrosoamides behave in a similar fashion to IV-nitrosoamines.60... [Pg.18]

By reacting 2-amino-3,4,5,6-tetrahydropyridine (118) with ethyl aceto-acetate or ethyl benzoyl acetate in pyridine, Wamhofif and Lichtenthaler178 obtained 1 4 equilibrium mixtures of the tautomers 119 and 120. [Pg.274]

To a solution of the (+)-methyl 2-[2-(N-phenylsulfonyl)indolyl]-2-hydroxy-3-[3-(N-allyl-5-ethyl-l,2,3,6-tetrahydropyridine)]propionate (a mixture of diastereomers at C-2) in dry dimethoxyethane at -50°C under argon was added sodium naphthalenide (1 M in THF). The mixture was quenched with trifluoroacetic acid, and extracted with ethyl acetate (3 times 10 ml). The extract was washed with saturated aqueous NaHC03 solution, dried (MgS04) and evaporated in vacuo to give the (+)-methyl 2-(2-indolyl)-2-hydroxy-3-[3-(N-allyl-5-ethyl-l,2,3,6-tetrahydro-pyridine )]propionate. The mixture of diastereomers was not separated but chromotagraphed over silica gel eluting with hexane/ethyl acetate/10% aqueous NH4OH/MeOH (5 1 1) to remove more polar impurities. [Pg.3443]

A mixture of 12.5 g of 2-(2-bromoethyl)naphthalene, 14.0 g of 4-(3-trifluoromethylphenyl)-l,2,3,6-tetrahydropyridine hydrochloride, 4.34 g of sodium hydroxide, 135 ml of water and 95 ml of 95% ethanol is refluxed for 5 h, the reaction mixture is subsequently allowed to cool to room temperature overnight and then filtered and the product isolated in this way is washed with water and dried under vacuum at 50°C to give l-[2-(2-naphthyl)ethyl]-4-(3-trifluoromethylphenyl)-l,2,3,6-tetrahydropyridine (yield of 90%, calculated relative to the starting 4-(3-trifluoromethylphenyl)-l,2,3,6-tetrahydropyridine hydrochloride). [Pg.3467]

The initial step in the reaction could be the addition of a Ti-Si species across the C=N bond of the pyridine to give an /V-silyldi hydropyridine. An additional two hydrogen atoms can be transferred to produce the tetrahydropyridine, but complete reduction only occurs in the presence of H2. On the other hand, electron-donating substituents and electron-withdrawing substituents on pyridine derivatives affect the reactions in different ways. 3-Picoline with electron-donating substituents gives two hydrogenation-hydrosilation isomers in a 3 2 ratio in 85% yield [Eq. (24)] whereas ethyl nicotinate with... [Pg.164]

The 4-methoxy-l,2,3,4-tetrahydropyridine 224 undergoes thermal [2+2] cycloaddition to ethyl propiolate to give 1,6,7,8-tetrahydroazocine 225 which can be isomerized under acidic reducing conditions to 1,2,7,8-tetrahydroazocine 226 with concomitant elimination of methanol (Scheme 58) <2000TL6067>. Replacement of sodium borohydride with an alkyl Grignard reagent in the isomerization procedure results in formation of 2-alkyl-substituted products <2005EJ01052>. [Pg.204]

Ethyl l,2,4-triazine-3-carboxylate (25) underwent a Diels-Alder reaction with ferf-butyl 4-(pyrrolidin-1 -yl)-1,2,3,4-tetrahydropyridine-1 -carboxylate (24) to give ethyl 6-ferf-butoxycarbonyl-5,6,7,8-tetrahydro-2,6-naphthyridine-l-carboxylate (26) as a minor product (CHC13, 20°C 8%).941... [Pg.265]

Tietze and Schuffenhauer explored the intermolecular hetero Diels-Alder reaction of ethyl vinyl ether and sulfinimine 204 and found that at high pressures (11 kbar) and long reaction times (48 h at room temperature), tetrahydropyridines 205 and 206 were obtained in 96% yield and in a ratio of 1.7 1.107 The exo-adducts were not observed. Phenyl vinyl sulfide reacts similarly, but simple alkenes failed. Theoretical calculations and the experimental results suggest that while the cycloaddition is concerted, it is highly asynchronous. [Pg.277]

Tetrahydroazocines. Tetrahydropyridines 34, obtained in four steps from readily available 3-a 1 ky 1 -N-benzyl-pyridinium salts, were used in the preparation of functionalized azocine derivatives 36 via their corresponding iminium salts (Scheme 9 <2005EJ01052, 2000TL6067>). Tetrahydropyridines were heated with ethyl propiolate in refluxing MeCN for 2 h to yield compounds such as 36 in good to excellent yields. [Pg.8]

Ethyl 5-Fluoro-6-hydroxy-l-tosyl-l,2,3,6-tetrahydropyridine-2-carboxylate (27) Typical Procedure ... [Pg.652]


See other pages where 2-Ethyl-tetrahydropyridine is mentioned: [Pg.83]    [Pg.220]    [Pg.303]    [Pg.19]    [Pg.246]    [Pg.828]    [Pg.2335]    [Pg.148]    [Pg.189]    [Pg.338]    [Pg.47]    [Pg.113]    [Pg.465]    [Pg.485]    [Pg.626]    [Pg.236]    [Pg.180]    [Pg.80]    [Pg.246]    [Pg.181]    [Pg.202]    [Pg.61]    [Pg.515]    [Pg.709]    [Pg.1419]    [Pg.465]    [Pg.485]   
See also in sourсe #XX -- [ Pg.636 ]




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Tetrahydropyridines

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