4- -l,3-dioxolanes

The dipole moments of the two conformers 146 and 147 of 1-rm-butyl-piperidine-4-spiro-4 (l, 3 -dioxolan) were calculated by vector addition of the moments of 1-fert-butylpiperidine and 4,4-dimethyl-1,3-dioxolan, making reasonable assumptions regarding geometries. This gave 1.15 and 1.93 D as the moments of the two conformers. The observed moment of 1.47 D gave AG° of 0.37 kcal mol-1 in favor of the axial oxygen conformer 146 in cyclohexane solution. AG%2- of 0.26 kcal mol-1 was estimated from low-temperature H-NMR studies.121 The differences between the piperidine and... 

Androstanc-( 17-spiro-4 )-1,3-dioxo-lane-(5-spiro-4>-l,3-dioxolane... 

Oxalyl chloride (5.25 ml) dissolved in 8.58 ml DMSO and CH2C12 was cooled to —78°C, then treated with l-[(.S )-2,2-dimc(hyl-(l,3)-dioxolan-4-yl]-4-(l,3-dioxolan-2-yl)-2-ol (54.9 mmol) followed by 38.2 ml triethylamine after 15 minutes. The solution was warmed, concentrated, the residue purified by flash chromatography with silica gel using 20% EtOAc/hexanes, and the product isolated in 95% yield as yellow oil. 

A general route to vinylcyclohexanones has been developed which depends on the diphenyl disulfide catalyzed combination of functionalized alkenes with a unique 2-vinylspiro[cyclo-propane-l,4 -l,3-dioxolane] reagent 7. Phenylsulfanyl radicals generated from the catalyst undergo addition to the vinyl group of 7 the resulting cyclopropylmethyl radical undergoes... 

FDA and urea for few hours [179, 180]. Some of the NLO chromophores [179, 180] used in this method are 2-[3-(2- 4-[bis-(2-hydroxy-ethyl)-amino]-phenyl -vinyl)-5,5-dimethyl-cyclohex-2-enylidene]-malononitrile [179], 4-[N,N-bis(hydroxyethyl)amino]-4 -nitrostilbene [179], 4-[N,N-bis(hydroxyethyl)amino]-4 -nitroazobenzene [179], 4-[N,N-bis(hydroxyethyl)amino]-2 -methyl-4 -nitroazobenzene [179], 4-[N,N-bis (hydroxyethyl) amino]-4 -cyanoazobenzene [179],4-[N,N-bis(hydroxyethyl)amino]-4 -formylazobenzene [180] and 2-[[4-(4-[l,3]dioxolan-2-yl-phenylazo)-phenyl]-(2-hydroxy-ethyl)-amino]-ethanol [180] and their chemical structures are given in figure 34. 

PEROXIDES AND PEROXIDE COMPOUNDS - ORGANIC PEROXIDES] (Vol 18) cis-4-Hydroxymethyl-2-iodomethyl-l,3-dioxolane [61508-55-2]... 

Perfluoroepoxides have also been prepared by anodic oxidation of fluoroalkenes (39), the low temperature oxidation of fluoroalkenes with potassium permanganate (40), by addition of difluorocarbene to perfluoroacetyl fluoride (41) or hexafluoroacetone (42), epoxidation of fluoroalkenes with oxygen difluoride (43) or peracids (44), the photolysis of substituted l,3-dioxolan-4-ones (45), and the thermal rearrangement of perfluorodioxoles (46). 

Miscellaneous OC-Substituted Peroxides. 3-Aryl-3-(/ i alkylperoxy)-phthaHdes (12) are prepared from the corresponding 3-chlorophthaHdes and alkyl hydroperoxide (156). 2-Methyl-2-(/ f2 -alkylperoxy)-l,3-benzodioxan-4-ones (13) are obtained from 0-acetylsaHcyloyl chloride and alkyl hydroperoxides (157). Trisubstituted 2-(/ f2 -alkylperoxy)-l,3-dioxolan-4-ones (14) are synthesized from stericaHy favored a-acyloxy acid chlorides and alkyl hydroperoxides (158). 

Condensation of vinyl chloride with formaldehyde and HCl (Prins reaction) yields 3,3-dichloro-l-propanol [83682-72-8] and 2,3-dichloro-l-propanol [616-23-9]. The 1,1-addition of chloroform [67-66-3] as well as the addition of other polyhalogen compounds to vinyl chloride are cataly2ed by transition-metal complexes (58). In the presence of iron pentacarbonyl [13463-40-6] both bromoform [75-25-2] CHBr, and iodoform [75-47-8] CHl, add to vinyl chloride (59,60). Other useful products of vinyl chloride addition reactions include 2,2-di luoro-4-chloro-l,3-dioxolane [162970-83-4] (61), 2-chloro-l-propanol [78-89-7] (62), 2-chloropropionaldehyde [683-50-1] (63), 4-nitrophenyl-p,p-dichloroethyl ketone [31689-13-1] (64), and p,p-dichloroethyl phenyl sulfone [3123-10-2] (65). 

Calculation of group increments for oxygen, sulfur and nitrogen compounds has allowed the estimation of conventional ring-strain energies (CRSE) for saturated heterocycles from enthalpies of formation. For 1,3-dioxolane, CRSE is about 20 kJ mol . In 2,4-dialkyl-l,3-dioxolanes the cis form is always thermodynamically the more stable by approximately 1 kJ mol" . 

Oxetan-3-one, 2-[2,2-dimethyl-4-(2,2-dimethyl-l,3-dioxolan-4-yl)-1,3-dioxolan-5-yl]-4-methyl-X-ray, 7, 366 <76JCS(P2)1678)... 

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