Homolytic telomerization of vinyltrimethylsilane with 5,5-dimethyl-1,3-dioxane

The homolytic telomerization of vinyltrimethylsilane by 5,5-dimethyl-1,3-dioxane follows three principal routes, with the formation of 2- and 4-substituted 5,5-dimethyl-1, 3-dioxanes and a formate ester. The rings in the reaction products (2-trimethylsilylethyl- and 4-trimethylsilylethyl-5,5-dimethyl-1,3-dioxane) exist in the chair conformation. The substituants in the 2- and 4-positions of the dioxane ring occupy equatorial positions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1031–1035, August, 1986.     

Synthesis of 2-aryl-3-hydroxymethyl-5,5-difluoropiperidines

A strategy toward the synthesis of functionalized 5,5-difluoropiperidines, a class of compounds with potential as building block in medicinal chemistry, was developed. In a three-step procedure 2,2-difluoroglutaric anhydride was synthesized starting from ethyl bromodifluoroacetate. This key intermediate reacts fluently with various imines to yield 5,5-difluoropiperidinone carboxylic acids. Subsequent esterification of the obtained carboxylic acids enabled the isolation of trans-substituted 5,5-difluoro-2-arylpiperidinone-3-carboxylates as the major isomers. Reduction of the difluorinated piperidinonecarboxylates using borane gave rise to new trans-2-aryl-1-benzyl-5,5-difluoro-3-hydroxymethylpiperidines in excellent yields.     

5,5'-Azoxytetrazolates - a new nitrogen-rich dianion and its comparison to 5,5'-azotetrazolate

A modification of the synthesis of sodium 5,5'-azotetrazolate pentahydrate, described by Thiele in 1898, yields the unknown and unexpected corresponding 5N-oxido derivative sodium 5,5'-azoxybistetrazolate pentahydrate (Na(2)zTO·5H(2)O, ). Purification was achieved by recrystallization based on the better solubility of Na(2)zTO·5H(2)O in water. Different nitrogen-rich salts, such as the diammonium (), the dihydroxylammonium (), the bis-diaminoguanidinium (), the bis-triaminoguanidinium () and the diaminouronium salt (), have been prepared using metathesis reactions starting from barium 5,5'-azoxybistetrazolate pentahydrate () and ammonium, hydroxylammonium, diaminoguanidinium or diaminouronium sulfate and triaminoguanidinium chloride, respectively. The nitrogen rich azoxy-derivatives were characterized using NMR, IR and Raman spectroscopy, mass spectrometry and elemental analysis. Additionally the solid state structures of , , and were determined by single crystal X-ray diffraction. The heats of formation of and and their corresponding azo-tetrazolate derivatives were calculated by the atomization method based on CBS-4M enthalpies. With these values and the crystal densities, several detonation parameters such as the detonation velocity, detonation pressure and specific impulse were calculated (EXPLO5) and compared. The sensitivities towards shock (BAM drophammer), friction (BAM friction tester) and electrostatic discharge of the described compounds were determined.     

Simplified synthesis of isotopically labeled 5,5-dimethyl-pyrroline N-oxide

5,5-Dimethylpyrroline N-oxide (15N) and 5,5-di(trideuteromethyl)pyrroline N-oxide were synthesized from the respective isotopically labeled 2-nitropropane analogs obtained from the reaction of sodium nitrate with 2-halopropanes. This facile, straightforward process allows synthesizing isotopically labeled DMPO analogs in a 4-step reaction without special equipment.     

Synthesis and reactions of 2-hydroxy-5,5-dimethyl- and 2-hydroxy-5,5-pentamethylene-2-trifluoromethyltetrahydro-4-pyranones withN-nucleophiles

Condensation of 4-hydroxy-3,3-dimethyl- and 4-hydroxy-3,3-pentamethylenebutan-2-ones with ethyl trifluoroacetate in the presence of LiH in hexane afforded 2-hydroxy-5,5-dimethyl-and 2-hydroxy-5,5-pentamethylene-2-trifluoromethyltetrahydro-4-pyranones, whose behavior in reactions withN-nucleophiles is analogous to that of unsymmetrical polyfluorinated β-diketones. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1201–1205, June, 1998.     

Mechanistic studies in the attempted synthesis of 5,5-dimethyl-2-isopropylidene-1,3-cyclohexanedione

In contrast to the corresponding cyclopentanedione derivative, 5,5-dimethyl-2-isopropyl-2-phenylsulfinyl-1,3-cyclohexanedione (3) does not undergo the expected cis-elimination of phenylsulfenic acid on warming in CH₂Cl₂ to afford the title compound 1, but instead gives an equimolar mixture of 5,5-dimethyl-2-(1 ′-isopropyl-4′,4′-dimethyl-2′,6′-dioxocyclohexyl)-2-isopropyl-1, 3-cyclohexanedione (9) and S-phenyl benzenethiosulfonate (10). These products result from dimerization of the 4,4-dimethyl-1-isopropyl-2,6-dioxocyclohexylradical (7) andthephenylsulfinyl radical (8), respectively. Diploma Thesis, University of Hamburg, 1990.     

N-acyl-5,5-dimethyloxazolidin-2-ones as latent aldehyde equivalents

A study of the properties of N-hydrocinnamoyl- derivatives of 5,5-dimethyloxazolidin-2-one, 4,4-dimethyloxazolidin-2-one and oxazolidin-2-one upon hydride reduction with DIBAL-H demonstrates that the 5,5-dimethyl-group is essential for inhibition of endocyclic nucleophilic attack. For instance, treatment of N-hydrocinnamoyl-5,5-dimethyloxazolidin-2-one with DIBAL-H results in the selective formation of the stable N-1'-hydroxyalkyl derivative which may be regarded as a masked hydrocinnamaldehyde equivalent, as treatment under basic conditions affords the parent aldehyde in excellent yield. Treatment of N-hydrocinnamoyl-4,4-dimethyloxazolidin-2-one with DIBAL-H under identical conditions affords a complex mixture of products, including the formate ester product of endocyclic cleavage. As an alternate strategy, DIBAL-H reduction of straight chain and branched N-acyl-5,5-dimethyloxazolidin-2-one derivatives, followed by a Horner-Wadsworth-Emmons reaction affords alpha,beta-unsaturated esters in good yields. Branching alpha- to the exocyclic carbonyl in N-acyl-oxazolidinones inhibits DIBAL-H reduction, but this can be overcome by precomplexation with ZnCl2, with subsequent fragmentation generating either the corresponding aldehyde or alpha,beta-unsaturated esters. The addition of ZnCl2 has been shown to increase the diastereoselectivity observed in Wadsworth-Horner-Emmons reactions of lithiated phosphonates.     

Photochemistry of 5,5-Dimethyl-2(5H)-thiophenone

On irradiation (λ > 305 nm) in alcohols, 5,5-dimethyl-2(5H)-thiophenone ( 1b ) is converted to (E)-4-mercapto-4-methyl-2-pentenoates 8 . These esters undergo a consecutive light-induced reaction affording thiolanes when irradiated in the presence of alkenes, and either 2,3-dihydrothiophenes or 3-thiabicyclo[3.1.0]hexanes with alkynes.     

5,5'-Methylenebis(4,6-dihydroxy-2-methylthiopyrimidines)

5,5'-Methylenebis(4,6-dihydroxy-2-methylthiopyrimidines) were synthesized by condensation of 4,6-dihydroxy-2-methylthiopyrimidine with formaldehyde and aromatic or heterocyclic aldehydes in ethanol. According to the spectral data and PM3 quantum-chemical calculations, the most favorable tautomers of 5,5'-methylenebis(4,6-dihydroxy-2-methylthiopyrimidine) are those stabilized by intramolecular hydrogen bonds between the OH group of one pyrimidine fragment and the CÍO groups of the other.     

3-acyl-1,5-benzodiazepines in the reactions of 5,5-dimethyl-2-formylcyclohexane-1,3-dione with certain 1,2-diaminobenzenes

Reaction of 5,5-dimethyl-2-formylcyclohexane-1,3-dione with 4-methyl-, 4-benzoyl-, and 4-nitro-1,2-diaminobenzenes gave the corresponding 2-(2-amino-4-methylphenylaminomethylene)-, 2-(2-amino-5-benzoylphenylaminomethylene)-, and 2-(2-amino-5-nitrophenylaminomethylene)-5,5-dimethylcyclohexane-1,3-diones. When treated with hydrochloric acid, they cyclize to 7-methyl-, 8-benzoyl-, and 8-nitro-3,3-dimethyl-2,3,4,5-tetrahydro-1H-dibenzo[b,e][1,4]diazepinon hydrochlorides. Under hydrolytic conditions the salts of 3,3,7-trimethyl-2,3,4,5-tetrahydro-1H-dibenzo[b,e][1,4]diazepinone and 3,3-dimethyl-2,3,4,5-tetrahydro-1H-dibenzo[b,e][1,4]diazepinone undergo the C₁₁−N₁₀ bond cleavage to give N-(2-aminophenyl)- and N-(2-amino-5-methylphenyl)-substituted 3-amino-2-formyl-5,5-dimethylcyclohex-2-enones. Ring opening of the hydrochlorides of 8-benzoyl-, and 3,3-dimethyl-8-nitro-2,3,4,5-tetrahydro-1H-dibenzo[b,e][1,4]diazepinones occurs at the C−N₅ bond and gives the starting enamines. Riga Technical University, Riga LV-1658, Latvia; Translated from Khimiya Geterotsiklicheskikh Soedinenii, N. 5, pp. 696–700, May, 1999.     

1,7-dithioxo systems. Reaction of 3-[(5,5-dimethyl-3-thioxocyclohex-1-en-1yl)sulfanyl]-5,5-dimethylcyclohex-2-ene-1-thione with 2-aminoethanol and ethane-1,2-diamine

The reaction of 3-[(5,5-dimethyl-3-thioxocyclohex-1-en-1-yl)sulfanyl]-5,5-dimethylcyclohex-2-ene-1-thione with 2-aminoethanol involves cleavage of the sulfide bond with formation of 3-[(2-hydroxyethyl)-amino]-5,5-dimethylcyclohex-2-ene-1-thione as the major product. The reaction of the same sulfide with ethane-1,2-diamine gave previously unknown 3-({2-[(5,5-dimethyl-3-thioxocyclohex-1-en-1-yl)amino]ethyl}-amino)-5,5-dimethylcyclohex-2-ene-1-thione.     

Synthesis of some novel chloro-/aryl-substituted-5,5-dimethyl-2-cyclohexenones

Abstract

Two novel structural isomers: the dihalo-5,5-dimethyl-2-cyclohexenones were synthesized. Regioselective Suzuki-Miyaura cross coupling reaction of the isomers with nine different aryl boronic acids afforded eighteen novel compounds: the 2-aryl-3-chloro-5,5-dimethyl-2-cyclohexenones and the 3-aryl-2-chloro-5,5-dimethyl-2-cyclohexenones in 90–95% yields, which were characterized spectroscopically by IR, NMR and MS. The single crystal X-Ray diffraction ORTEP views of four representative compounds unambiguously confirm the formation of substituted cyclohexenones.     

5,5-Dimethyl-2-phenylamino-2-oxazoline as an effective chiral auxiliary for asymmetric alkylations

The novel chiral auxiliaries, 5,5-diphenyl-2-phenylamino-2-oxazoline and 5,5-dimethyl-2-phenylamino-2-oxazoline, were prepared from l-valine methyl ester. The 5,5-dimethyl compound was shown to be a particularly effective chiral auxiliary for asymmetric alkylation affording high yields and diastereoselectivities.     

Synthesis of 5,5-bis(difluoroamino)-2-hexanone

Conclusions A method was developed for the preparation of 5,5-bis(difluoroamino)-2-hexanone by the acid hydrolysis of the sodium salt of 2-nitro-5,5-bis(difluoroamino)hexane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2145–2146, September, 1973.     

Synthesis of 2-cyclopentyloctane and 5,5-dimethylundecane

Summary 2-Cyclopentyloctane and 5,5-dimethylundecane were prepared for the first time. Their synthesis and properties are described.     

Ring inversion in 5,5-disubstituted 1,3-dioxanes

The conformational mobility was studied by dynamic PMR and the free energies of activation of the conformational transitions of 5,5-bis(chloromethyl)-, 5,5-bis(iodomethyl)- and 2,3-pentamethylene-bis-5,5-bis(chloromethyl)-1,3-dioxanes were determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 607–608, May, 1987.     

水溶剂中芳醛与5，5－二甲基－1，3－环己二酮的反应

芳醛1与5，5－二甲基－1，3－环己二酮（2）在氯化三乙基苄基铵（TEBA）催 化下在水中生成2，2'－芳业甲基双（3－羟基－5，5－二甲基－2－环己烯－1－酮 ）（3），若在体系中有对甲苯磺酸存在时则生成3，3，6，6－四甲基－9－芳基－ 1，8－二氧代八氢化氧杂蒽（4）或3，3－二甲基－9－（3－羟基－5，5－二甲基 －2－环己烯－1－酮－2－基）－1－氧代四氢代氧杂蒽（6）而不是生成3，产率接 近定量。     

1,7-Dithioxo Systems. Synthetic Routes to Bis(5,5-dimethyl-3-thioxo-1-cyclohexenyl) Sulfide

Synthetic routes to bis(5,5-dimethyl-3-thioxo-1-cyclohexenyl) sulfide have been studied. The title compound can be obtained by reaction of 3-chloro-5,5-dimethyl-2-cyclohexenethione with sodium thiosulfate and by condensation of 3-mercapto-5,5-dimethyl-2-cyclohexenethione. The reaction of bis(5,5-dimethyl-3-oxo-1-cyclohexenyl) sulfide with hydrogen sulfide and hydrogen chloride yields 3-oxo-3'-thioxobis(5,5-dimethyl-1-cyclohexenyl) sulfide.     

Synthesis of 2-Aryl and 2-Hetaryl Derivatives of 2'-Aminospiro[(1,3-dioxane)-5,5'-thiazolin]-4'-one and Spiro[(1,3-dioxane)-5,5'-thiazolidine]2',4'-dione

2-(Het)aryl derivatives of 2'-aminospiro[(1,3-dioxane)-5,5'-thiazolin]-4'-one or spiro[(1,3-dioxane)-5,5'-thiazolidine]-2',4'-dione are formed by the acid catalyzed interaction of 2-amino-5,5-bis(hydroxymethyl)-4-thiazolinone or its oxo analog 5,5-bis(hydroxymethyl)thiazolidine-2,4-dione with (hetero)aromatic aldehydes.     

Reaktionen des 5,5-Diphenyl-4-hydroxy-1,2,3-triazols

Zusammenfassung Es werden einige Reaktionen des aus aktiven Estern der -Zzidodiphenylessigsäure leicht zugänglichen¹ 5,5-Diphenyl-4-hydroxy-1,2,3-triazols beschrieben.