2- Phenyl-1,3-dioxanes

Aspects of Stereochemistry, Part IV. Configuration and Some Reactions of 1 3-0-Benzylideneglyc-erols (5-Hydroxy-2-phenyl-1 3-dioxans), N. Baggett, J. S. Brimacombe, A. B. Foster, M. Stacey, and D. H. Whiffen,7. Chem. Soc., (I960) 2574-2581. 

Bender ML, Silver MS (1963) The hydrolysis of substituted 2-phenyl-1,3-dioxane. J Am Chem Soc 85 3006-3010... 

Table 4(a) Conformational equilibria in 5-substituted-2-phenyl-1,3-dioxanes 68-72 in different solvents subject to the presenoe of salt ... 

K2CO3 and distd under reduced pressure. More extensive purification involved conversion with benzaldehyde to 2-phenyl-1,3-dioxane (m 47-48°) which was subsequently decomposed by shaking with 0.5M HC1 (3ml/g) for 15min and standing overnight at room temperature. After neutralisation with K2CO3, the benzaldehyde was removed by distn and the diol was recovered from the remaining aqueous soln by continuous extraction with... 

Fukuzawa et al.245 used 2-phenyl- 1,3-dioxane to benzylate a variety of arenes [Eq. (5.91)]. Similar observations were made when substituted benzaldehydes were treated in the presence of 1,3-propanediol under identical conditions. Although 2-phenyl-1,3-dioxane gave similar results, benzaldehyde dialkylacetals in general were unreactive under similar conditions. Mechanistic studies including reaction of a labeled dioxane indicate the involvement of the alkylated intermediate 65 and product formation was interpreted via an 1,3-hydride shift. 

Table VIII. Conformational Equilibria of 5-Substituted 2-Phenyl-1,3-dioxanes Dependent on the Presence of LiBr at 25 °C in THF...

DIMETHYLAMINO)-N-(((METHYL(((2-PHENYL-1,3-DIOXAN-5-YL)METHO-XY) SULFINYL)AMINO)CARBONYL)-OXY)-2-OXO-ETHANIMIDOTHIOIC ACID, METHYL ESTER mf C18H25N3O7S2 mw 459.58... 

From 1988 to 1990, Ihara and co-workers modified the above synthesis approach to develop an asymmetric total synthesis of (-)-tylophorine [(-)- ] via an intramolecular double Michael reaction of a,p-imsaturated esters. Their work proved that the absolute configuration of naturally occurring (-)-tylophorine is (R). Two different chiral auxiliaries, (-)-phenylmenthol [52, 53] or (2R,4S,5R)-(-)-4-(tert-butyldimethylsiloxymethyl)-5-hydroxy-2-phenyl-1,3-dioxane(BDH), were employed [53, 54]. The reactions are summarized in Scheme (2). The resulting (E, E)-esters (26) and (27) underwent a double Michael reaction through proposed transition states (A) (B), respectively, to give a highly enantioselective product (28 and 29, respectively). (-)-... 

Reductions. Aldehydes, aromatic acids and their esters are reduced by PMHS in the presence of Bu NF. Aluminum chloride is also an effective catalyst in the selective reductive cleavage of 2-phenyl-1,3-dioxanes and dioxolanes (e.g., 4-O-benzyl derivatives from the 4,6-benzylidene sugars).- ... 

Let us now consider 2-phenyl-1,3-dioxan-5-one and compare its selectivity profile with that of 4-ferf-butylcyclohexanone in reactions with Grignard reagents, see Table 2. In 2-phenyl-1,3-dioxan-5-one, ctC4 o3 —> tt c=o and crC6 (,i > jt c=G... 

Hydroxy-2-phenyl-1,3-dioxane. See Benzaldehyde glyceryl acetal 4-Hydroxy-m-phenylenediammonium dichloride. See 2,4-Diaminophenol hydrochloride 1-(3-Hydroxyphenyl) ethanone 1-(3-Hydroxyphenyl) ethan-1-one. See m-Hydroxyacetophenone... 

Phenyl-2-cyclopenten-l-one -Phenyl-A/,APdielhanolamine 2-Phenyl-1,3-dioxane 4-Phenyl-1,3-dioxane... 

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