Dioxane Derivatives

Condensation of tetrachloro-l,2-benzoquinone or 2,3-dichloro-l,4-naph-thoquinone with o-dihydroxyarenes, alone or in the presence of copper and its salts, yields 379 or 380 (OIJAIO 07JA7 08JA499 21CB259 52JCS489 78IZV204). 

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The presence of twist-boat forms in the conformational equilibria of 1,3-dioxane derivatives due to the presence of 1,3-diaxial interactions was corroborated by force field calculations [77T2237 79T691, 79T1945]. 

Table 5 NMR assignment of stereochemistry and erythro/threo-conf gurat on of 4,5-disubstituted-1,3-dioxane derivatives 73...

Table 12 Diastereoselective hydroformylation of 4-methylene-1,3-dioxane derivatives r2 H2, CO d2...

Keywords styrene, TaCls-Si02, paraformaldehyde, microwave irradiation, Prins reaction, 1,3-dioxane derivative... 

Styrene (1.04 g, 0.01 mol) and paraformaldehyde (0.9 g, 0.01 mol) were adsorbed on activated silica gel (2 g, 100-200 mesh, dried overnight at 110°C) and stirred at room temperature for 1 h under N2 atmosphere. To this TaCl5-Si02 (0.37 g, 10 mol%) was added and admixed thoroughly and irradiated in a microwave oven (600 W) for 3 min. This mixture was cooled to room temperature, charged on a small silica pad and eluted with n-hexane-ethyl acetate mixture (80 20). Removal of volatiles furnished 1,3-dioxane derivative 2 (1.48 g, 90%). 

Formaldehyde reacts with isoeugenol [l-(3-methoxy-4-hydroxyphenyl)propene] in alkaline medium to give a 1,3-dioxane derivative via an unusual Prins-type reaction.192... 

The substitutions by o-nitrobenzyl groups are used for dioxolane and 1,3-dioxane derivatives, but the photochemical cleavage is only partially regioselective. However,... 

The occurrence of a back-biting reaction is further indicated by the observation that in copolymerizations of trioxane or tetroxane with vinyl monomers various 1,3-dioxane derivatives are formed (29,56). With styrene for example, the derivative was 4-phenyl-l,3-dioxane, the formation of which was explained as follows ... 

During a synthesis of the antibiotic 1233A, a Hofmann-La Roche group investigated the isopropylidenation of the triol 35 1 under both kinetic and thermodynamic conditions [Scheme 335].18 All three possible 1,3-dioxane derivatives... 

Three modes of reaction of aldehydes with allylsilane bearing sterically demanding silyl substituents are mediated by the proper choice of Lewis acid (Eq. 39) [66a]. Thus, influenced by SnC, allyl-t-butyldimethylsilane reacts with aldehyde in 2 1 stoichiometry to afford a ketone derivative. In contrast, use of BF3 OEt2 leads to the formation of a 1,3-dioxane derivative, which is a 1 2 adduct. Furthermore, ZrCU-pro-moted [2 -r 2] cycloaddition of allylsilane and aldehyde fnmishes oxetanes in good yields [66b]. 

Kinetics of isomerization of glyceraldehyde to dihydroxyacetone—and the formation of pyruvaldehyde from both— have been studied in sub- and super-critical water. Formaldehyde reacts with isoeugenol [l-(3-methoxy-4-hydroxyphenyl)propene] in alkaline medium to give a 1,3-dioxane derivative via an unusual Prins-type reaction. The potential-energy surface for the equihbriimi, HCO - - HCN H2CO - - CN, has been calculated by ab initio methods. 

The exchange of alkoxy groups for the cyanide function can also be achieved in acetals (cyclic types like dioxolanes and 1,3-dioxane derivatives included), 5A -acetals and ortho esters with the combination of TMS-CN/Lewis acids, or under neutral conditions with transition metal salts as catalysts (Scheme 16). Furanose derivatives may be treated with TMS-CN in a similar way. ... 

Yadav, J. S., Reddy, B. V. S., Bhaishya, G. lnBr3-[bmim]PF6 a novel and recyclable catalytic system for the synthesis of 1,3-dioxane derivatives. Green Chem. 2003, 5, 264-266. 

The dependence of the magnitude of the coupling constant Jc—p on the position of phosphorus in 2-P-substituted 1,3-diheteroanes was discussed in Section IV.B.3.b. While the argument supports ny-negative hyperconjugation as a source of the anomeric effect in 1,3-dioxane derivatives as well as in all phosphonium salts, the relationship between the Jc—p coupling constant through the axial and equatorial C(2)—P bonds in nonionic... 

Formaldehyde can be coupled to an alkene in the presence of an acid to give a diol (152) or a 1,3-dioxane derivative (154) in what is known as the Prins reaction. l Allylic alcohols such as 153 can also be produced in this reaction. Camphene (155) reacted with formaldehyde and acid to give a 1 1 mixture of allylic alcohol 156 and the acetate 157, in 94% yield. Scandium tiiflate has been used to prepare tetrahydropyran-4-ol derivatives from aldehydes and homoallylic alcohols via a Prins-type cyclization. 3... 

Malinowski and T. Urbanski (60J advanced a suggestion that a hydrogen bond can exist between the nitro and the hydroxy group in nitro alcohols. This was based on the experimental fact that 2-nitropropane-l,3-diol (I) formed cyclic acetals-1,3-dioxane derivatives (II) and ketals with great difficulty, while on the contrary the triol 2-hydroxymethyI-2-nitro-propane-l,3-diol (11 ) forms the corresponding cyclic acetal (IV) and ketal with great ease. 

Recently the kinetics of this reaction has been studied in detail [146] The copolymers containing tertiary nitrogen with anchored Cu(I) or Cu(II) can be used in such reactions [147], The oxidation of methacrolein dimer and unsaturated 1,3-dioxane derivatives in the presence of polymer-supported Co(II) and Mn(II) complexes [148] also leads to a set of the products. Immobilized Pt complexes are also active in the oxidation of oxygen-containing substrates. 

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