Dioxans 2-phenyl-, derivatives

Other donor molecules react with phosphonitrilic compounds. Dioxane is said to facilitate the depolymerization of the high polymer (63) and of the phenyl derivatives (13). Acetone forms complexes with the amino acid derivatives of the tetramer (see p. 128 in ref. 3). It is possible that ether acts as a catalyst for the hydrolysis of the trimeric chloride. The effect of these solvents is subtle, since the solubilities of the trimeric chloride in ether, in pyridine, and in dioxane show no sign of any specific chemical interaction. 

Bertz showed that cuprates such as 460 added to cyclohexenone to give the 3-phenyl derivative (46 1) in optical yields of 0-50%Typical examples are R R N = (45,55)-(+)-5-amino 2,2-dimethyl-4-phenyl-1,3-dioxane (the reaction proceeded in 62% yield, 50% ee) (R) or (S) a-methylbenzylamine (70% yield, 30% ee) (R) or (5) a-(l-naphthyl)ethylamine (70% yield, 30% ee) and (-) a-2-naphthylethyl-amine (50% yield, 40%... 

Diphenyldiborane appears to be moderately stable toward disproportionation at room temperature (66, 74, 83), although at 100° C in dioxane a reaction which should have yielded this phenyl derivative resulted instead in the formation of triphenylborane and diborane (73). All attempts to obtain... 

The enamines derived from cyclic ketones give the normal alkylated products, although there is some evidence that unstable cycloadducts are initially formed (55b). Thus the enamine (28) derived from cyclohexanone and pyrrolidine on reaction with acrylonitrile, acrylate esters, or phenyl vinyl sulfone gave the 2-alkylated cyclohexanones (63) on hydrolysis of the intermediates (31,32,55,56). These additions are sensitive to the polarity of the solvent. Thus (28) in benzene or dioxane gave an 80% yield of the... 

An interesting method of forming 2-oxo-3-phenyltetrahydro-l,3 oxazine (19) and its derivatives was recently given by Gulbins et at. It consists of heating a 2-oxo-l,3-dioxane with phenyl isocyanate ... 

Reaction of anthanilic acid 112 with acid anhydrides afforded the corresponding imide derivatives 113. Subjecting 113 to intramolecular Wittig cyclization has been achieved by treatment with A-phenyl(triphe-nylphosphoranylidene)etheneimine in toluene or dioxane whereby the corresponding pyrroloquinolines 116 were obtained (94TL9229). The intermediate 115 resulting from the rearrangement of 114 could be isolated when the reaction was done at room temperature (Scheme 22). 

The phenyl ether linkage of butoxy substituted 44 was cleaved with boron tribromide to give a hexaphenol derivative (45) in 60% yield (Scheme 14). The hexaphenol derivative was found to be remarkably soluble in most polar organic solvents, such as ethanol, DMF, DMSO, and dioxane, as well as in aqueous base solution. Condensation with octanoic acid in the presence of DCC and catalytic H+ afforded the inverse ester (46) in high yield. 

Some cyclic thioacetals have an A-SE2 hydrolysis mechanism,206 as do some 2-aryl-2-methyl-l,3-dithianes, except for the 4-NO2 derivative, which looks more A2-like.207 In 10 vol% dioxane/aqueous HC104 mixtures, reactive 2-aryl-2-phenyl-l,3-dithianes are believed to have an A-SE2 hydrolysis mechanism, whereas the least reactive ones have an A2 mechanism.130 Isothiocyanates are believed to hydrolyze by a mechanism that involves simultaneous proton transfer to nitrogen and attack of water at carbon in a cyclic transition... 

The method outlined here competes well with the method developed earlier by Danheiser, et al.618 Its superiority is based on the fact that phenyl ester enolates give almost the same results as the S-phenyl thiolester enolates. However, handling the malodorous benzenethiol for the preparation of the active acid derivative and during workup of the p-lactone can be avoided. In addition, phenol is much cheaper than benzenethiol. The method is well suited for the preparation of p-lactones from symmetrical and unsymmetrical ketones. In addition to 3,3-dimethyM-oxaspiro[3.5]nonan-2-one, ( )-3-ethyl-1-oxaspiro[3.5]nonan-2-one and (3R, 4R )- and (3R, 4S )-4-isopropyl-4-methyl-3-octyl-2-oxetanone were prepared by this procedure in high yields (Notes 11 and 12). In the case of unsymmetrical ketones the less sterically crowded diasteroisomer is formed preferentially. With aldehydes as the carbonyl component the yields are unsatisfactory, because of the competitive formation of 1,3-dioxan-4-ones.6... 

DePuy, as early as 1966 [14], reported that cw-1-methyl-2-phenylcyclopropanol gave exclusively deuterated 4-phenyl-2-butenone in 0.1 M NaOD/D20/dioxane. However, homoenolates derived from simple cyclopropanols by base-induced proton abstraction fail to react with electrophiles such as aldehydes and ketones, which would afford directly 1,4-D systems. Lack of a reasonably general preparative method was another factor which impeded the studies of homoenolate chemistry. For this reason, in the past twenty years more elaborated cyclopropanols, which might be suitable precursors of "homoenolates", have been prepared and studied. 

Recently, commercially available (45,5S)-5-amino-2,2-dimethyl-4-phenyl-1,3-dioxane has been successfully employed (177) in the synthesis (Scheme 10) of the chiral 13-crown-4, (55)-169, 16-crown-5, (SS)-170, and 19-crown-6, (SS)- , derivatives. 

Dihydrocinnoline derivative 235 could be synthesized from the [2-(2,2-dimethoxyethyl)phenyl]hydrazine 234 via acid-catalyzed cyclization in dioxane. When methanol was used as solvent, a 3-methoxy-l,2,3,4-tetrahydrocinno-line 236 was formed (Scheme 62) <1995LA1303>. 

A similar spiro-fused starting material was prepared to study the thermolysis of a 1,3-dioxane analog. As found for the dithia compound (cf. Section 8.11.6.3.1), a carbene-derived dimer was formed as the major detectible product (20%) <2002TL1927>. Other products, such as tricycle 185, have been identified in subsequent studies <2004CJC1769>. However, phenyl substitution at G-4 provided completely different thermolysis products, probably via formation of an open-chain bis-radical. Thus, 3-phenyl-7-butyrolactone and, after CO2 extrusion, phenylcyclo-propane are the major reaction products (Scheme 58) <2002CJC1187>. 

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