Dioxabicyclo heptan-5-ones

The silver-salt method was used by Porter and Gilmore in one of the first syntheses of 2,3-dioxabicyclo[2.2.1]heptane 936). Reaction of bicyclopentane with 98% H202 and IV-bromosuccinimide (NBS) in ether at —41 °C afforded mainly a 1 1 mixture... 

To add to the silver salt (Eq. 19) and peroxymercuration (Eq. 34-36) methods of preparing dialkyl peroxides, a third mild alkylation procedure has been developed that involves the use of alkyl trifluoromethane sulphonates (triflates)55). The peroxide transfer reaction between bistributyltin peroxide and the bistriflate 58 of cis-1,3-cyclopentanediol provided one of the first syntheses of 2,3-dioxabicyclo[2.2.1]heptane 9 (Eq. 44, H for D Tf = 02SCF3)56). Because of the sensitivity of 9, it was necessary to carry out the reaction in vacuo with rapid transfer of the volatile products to a cold trap to avoid decomposition a yield of 22% was achieved. 

Figure 5.2.11. Cellulose pyrolysate obtained at 59(P C and separated on a methyl silicone with 5% phenyl silicone type column. 1 acetic anhydride, 2 pentanal, 3 2-hydroxybutanedialdehyde, 4 1,4-dioxadiene, 5 tetrahydro-2-furanmethanol, 6 2-(hydroxymethyl)-furan, 7 3-methyl-2-hexanone, 8 2-methoxy-2,3-dihydrofuran, 9 2(5H)-furanone, 10 1-acetyloxypropan-2-one, 11 hydroxycyclopentenone, 12 5-methylfurfural, 13 2,3-dihydro-5-methylfuran-2-one, 14 1-cyclopentylethanone, 15 2-hydroxy-3-methyl-2-cyclopenten-1-one, 16 3,5-dimethylcyclopentan-1,2-dione, 17 unknown, 18 3-ethyl-2,4(3H,5H)-furandione, 19 6-methyl-1,4-dioxaspiro[2,4]heptan-5-one, 20 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one, 21 1,4 3,6-dianhydro-a-D-glucopyranose, 22 5-(hydroxymethyl)-furfural, 23 4-cyclopenten-1,2,3-triol, 24 5-ethyl-3-hydroxy-4-methyl-tetrahydrofuran-2-one, 25 levoglucosan, 26 1,6-anhydro-p-D-glucofuranose.

Selective reduction of unsaturated endoperoxides. 2,3-Dioxabicyclo[2.2.1]-heptane (3) serves as a model of the prostaglandin endoperoxide (PGG2), involved in the biosynthesis of prostaglandins and also of thromboxanes and PGl2 (prostacyclin). One successful synthesis of 3 involved sensitized photooxygena-lion of cyclopentadiene to give the unstable heat-sensitive endoperoxide 2, which... 

Synthesis of Dioxabicyclo[2.2.1]heptan-5-ones and Dioxabicydo[3.2.1]octan-2-ones... 

The ring-opening reactions of dioxabicyclo[2.2.1]heptan-5-ones were studied by Winkler and co-workers and used in the synthesis of various oxygen heterocycles [136]. For example, treatment of dioxanorbornanes 155 with samarium iodide as well as with mineral acid led to cyclic hemiketals 156 and spiroketals 157 (Scheme 49). 

Bromomethyl)-4,7-dimethoxyfuro[2,3-rf]pyridazine Spiro [cyclopentane-1,3 -bicyclo [4.1.0]heptane] (lR,3/ ,5S)-c 6 o-l,3-Dimethyl-2,9-dioxabicyclo[3.3.1]nonane Spiro [5.7]trideca-1,4-dien-3-one 1 -Benzoyl-2-phenylaziridine... 

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