Cyclopentanones dimethyl acetals

In hydrogenolyses with HAICU, the dimethyl acetals of cyclobutanone and cyclohexanone are cleaved more slowly than that of 3-pentanone, while those of cyclopentanone and cycloheptanone are cleaved more rapidly (Table 1), as would be expected for a carbonium ion process. The differences in rate are small, suggesting that carbonium ion character is not strongly developed in the transition state. With the dimethyl acetal of 4-t-butylcyclohexanone, the hydride addition step occurs with strongly predominating axial addition when HAlCh is used Zn(BH4)2 with TMS-Cl, and TMS-H with TMSO-Tf are less selective (Table 2). Equatorial attack predominates, however, in the reduction of the ketone itself with TBDMS-H and TBDMS-OTf. ... 

Acetone, acetic acid (glacial), lower alcohols, alcohol/ diethyl ether, amyl acetate, M-butyl acetate, butyl lactate, 7-butyrolactin, cyclopentanone, diethyl acetate, diethyl ketone, N,N-dimethylacetamide, dimethyl carbonate, dimethyl cyanamide, dimethylformamide, dimethyl maleate, dimethylsulfoxide, 2-ethoxyethyl acetate, ethyl acetate, ethyl amyl ketone, ethylene glycol ethers, ethyl lactate, 2-hexanone, methyl acetate, methyl ethyl ketone, methyl propyl ketone, M-methylpyrrolidone-2, 2-octanone, 1-pentanone, M-pentyl acetate, pyridine ... 

Cyclohexanone Cyclopentanone trans-trans-2,4-Decadienal A-Decalactone Decanal dimethyl acetal... 

Methyl 4,6-O-methylene-o-D-mannopyranoside was the only product isolated from the LiBr-catalised transacetalation of the unprotected methyl glycoside with dimethojqmiethane. Cyclopentylidene derivatives of pentoses have been prepared in moderate yields by treatment of the free sugars with cyclopentanone in the presence of copper (II) sulphate and sulphuric acid. D-Xylose formed the diacetal (11) (also used in Scheme 3 below), whereas from D-ribose the 2,3-monoacetal (12) was obtained. A novel, selective synthesis of (5)-configurated 4,6-pyruvate acetals of methyl D-hexopyranosides is illustrated in Scheme 1. It relies on transacetalation from the dimethyl acetal of 3,4-dimethoxybenzophenone to give, after acetylation, preferentially the intermediate (13) with an axial aryl substituent which, on oxidation, suffers rapid degradation to a carboxylic acid group. ... 

Ethylcyclop entanon e 3-Pentyl cyclopentanone 6-Methyl-3,5-heptadien-2-one 6-Methyl-2-cyclohexen-l-one 2,3-Dihydrocarvone Unidentified dimethylacetophenone 2-Butyrylfuran Dimethyl disulfide 2,6-Dimethylpyridine Isobutylbenzene Unidentified acetal (mol mass 154) Isobutyronitrile... 

A series of 4-heteroaryl-5,6-di(2,5-dimethyl-3-thienyl)-2-phenyM//-l,6-thiazines 54 with photochromic properties was prepared by reacting 3-(2-(2,5-dimethylthiophen-3-yl)ethynyl)-2,5-di ethylthiophene with thiobenzamide and aldehydes <2005CHE86, 2005PS1503>. The acid-catalyzed cyclocondensation of cyclopentanone, aromatic aldehydes, ArCHO, and thiourea affords the cyclopenta[t ]l,3-thiazines 37 <2006PS1655>. Two equivalents of the aldehyde are required. The same products are isolated when 2,5-dibenzylidenecyclopentanones are treated with thiourea under the same conditions. 2-Amino-4i/-l,3-thiazines 184 are easily synthesized in one pot by the reaction of aromatic alkynes, R feCH, aromatic aldehydes, R CHO, and thiourea in the presence of TFA/acetic acid <2005OL3797>. 

This reaction has been applied to a great number of carbonyl compounds, e.g., cyclopentanone,27 1,3-cyclohexanedione,36 5,5-dimethyl-l,3-cyclohexanedione,S5 1-acenaphthenone,24,25 1,3-indane-dione,35 1,3-phenalanedione,85 86 sodium salts of 3-aryl-3-oxo-propanals,39 2,3-dihydrobenzo[6]thiophen-3-one,40 sodium benzoyl-acetate,41 benzoylacetonitrile,29 30,88 ethyl cyanoacetate,30 35 cyano-acetanilide,30 barbituric acid,35 rhodanine,35 jV-phenylrhodanine,37 and iV-methylenebenzothiazoline.37... 

Using 2,2-dimethylcyclobutanone [26a], as a specific example, initial excitation to produce an excited state species followed by a-cleavage would produce the acyl alkyl biradical [30]. Subsequent decomposition of [30] would then afford ester [27a] (via ketene), cyclopropane [28a], and acetal [29a], the observed photoproducts. The intermediacy of biradical [30] was supported by (a) the nearly exclusive formation of methyl acetate (as opposed to methyl isobutyrate), (b) the exclusive formation of the 5,5-dimethyl substituted acetal [29a] (as opposed to its 3,3-dimethyl substituted isomer), (c) its role as a common intermediate for all products, and (d) analogy to the photochemistry of cyclopentanones and cyclohexanones. Recently, Wasacz and Joullie have reported that photolysis of oxacyclohexanone [32] affords a 3% yield of acetal [29a] (18). It is conceivable that the formation of [29a]... 

Figure 5.2.10. Cellulose pyrolysate obtained at 59CP C by Py-GC/MS. The separation was done on a Carbowax type column. 1 CO2, 2 acetaldehyde, 3 acetone, 4 2-butanone, 5 2,3-butandione, 6 toluene, 7 water, 8 cyclopentanone, 9 methylfuran, 10 3-hydroxy-2-butanone, 11 hydroxypropanone, 12 cyclopent-1-en-2-one, 13 2-methylcyclopentenone, 14 acetic acid, 15 acetic acid anhydride, 16 furancarboxaldehyde, 17 methylcyclopentenone, 18 dimethylcyclopentenone, 19 5-methylfurancarboxaldehyde, 20 2,3-dihydro-2-furanone, 21 furan-2-methanol, 22 3-methylfuran-2-one, 23 2(5H)-furanone, 24 hydroxycyclopentenone, 25 3,5-dimethylcyclopentan-1,2-dione, 26 2-hydroxy-3-methyl-2-cyclopenten-1-one, 27 2-hydroxy-3-ethyl-2-cyclopenten-1-one, 28 2,3-dimethyl-2-cyclopenten-1-one, 29 phenol, 30 dimethylphenol, 31 3 thyl-2,4(3H,5H)-furandione, 32 3-butenoic acid, 33 1,4 3,6-dianhydro-a-D-glucopyranose, 34 5-(hydroxymethyl)-furfural.

Bromo-2-fluoro biphenyl intermediate, foam builders Alkenyl succinic anhydride intermediate, food additives Soy acid Stearyl alcohol intermediate, food emulsifiers Caprylic/capric acid Tallow acid intermediate, food supplements (tablet form) Cetyl alcohol intermediate, food wrap Vinylidene chloride monomer intermediate, fragrances p-t-Butyl toluene t-Butyl-m-xylene Citral Cyclopentanone Diethyl toluene diamine Dimethyl hexynediol 1,2-Methylenedioxybenzene 2-Methylpentanal Myrcene n-Propyl bromide intermediate, fragrances cosmetics Acetic anhydride n-Butyraldehyde n-Butyric acid Butyric anhydride 2-Ethylhexoic acid Isobutyric anhydride 2-Methylpropanal Propionic anhydride intermediate, fragrances personal care Butyric anhydride Isobutyric anhydride intermediate, free-radical polymerization initiators... 

Benzyl alcohol at 155.4°C Tetrahydrofuran, acetone-carbon disulfide mixtures, methyl ethyl ketone Toluene, xylene, methylene chloride, ethylene chloride, perchloroethylene-acetone mixtures, 1,2-dichlorobenzene, tetrahydrofurfuryl alcohol, dioxane, acetone-oarbon disulfide mixtures, cyclopentanone, diisopropyl ketone, mesityl oxide, isophorone, dimethyl-formamide, nitrobenzene, hexamethyl-phosphoramide, tricresyl phosphate Aliphatic and aromatic hydrocarbons, vinyl chloride monomer, alcohols, glycols, aniline, acetone, carboxylic acids, acetic anhydride, esters, nitroparaffins, carbon disulfide, nonoxidizing mineral acids, concentrated alkalies... 

Figure 3.3 Volatile degradation products in two oxidized polymers monitored by head-space GC. (a) Photo-oxidized LDPE with iron dimethyl dithiocarbamate and carbon black 1 = acetaldehyde 2 = methanol 3 = acetone 4 = 1-butanol 5 = butanol 6 = 3-pentanol. (b) Thermo-oxidized nylon 66 1 = acetaldehyde 2 = Cu-acetate 3 = cyclopentanone 4 = aniline.

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