Synthesis of diols

Adipoyl moiety is first attached ia order to provide an appropriately spaced proximal carbonyl group. The esters are oxidized enzymatically and then deacylated. The procedure results ia the synthesis of diols (119) with excellent enantiomeric purity (ee 96—98%) ia 72—92% yield. 

The synthesis of diol 56 from L-lyxose is reported. Compound 56 constitutes a subunit of the toxin erythroskyrine <96JCS(P1)1323>. 

SCHEME 20. Debromination of bromoalkenes 146. Synthesis of diols 151, O-protected a-alkoxy aldehydes 152 and Q-.o- -dialkoxyketones 153 G = protecting group... 

More recently, in light of the development of the Sharpless asymmetric dihydroxylation protocol [20], we have approached the synthesis of diols such as 14 (Scheme 2) from the alkene. Thus, treatment of the alkenyl D-glucosides 15 vmder the conditions of the Sharpless dihydroxylation gave a range of diols 16 with varying diastereoisomeric excesses (Table 1). One of these mixtures of diols, upon recrystallization, yielded the pure diastereoisomer, namely the diol 14. This procedure now gives a very rapid and efficient entry into one of the precursor diols for the synthesis of the optically-pure epoxides [21]. 

The Direct Enantioselective Synthesis of Diols from Olefins using Hybrid Catalysts of Chiral Salen Cobalt Complexes Immobilized on MCM-41 and Titanium-containing Mesoporous Zeolite... 

In conclusion, the chiral salen Co(III) complexes immobilized on Si-MCM-41 colud be synthesized by multi-grafting method. The asymmetric synthesis of diols from terminal olefins was applied with success using a hybrid catalyst of Ti-MCM-41/chiral Co(III) salen complexes. The olefins are readily oxidized to racemic epoxides over Ti-MCM-41 in the presence of oxidants such as TBHP, and then these synthesized diols are generated sequentially by epoxide hydrolysis on the salen Co(lll) complexes. This catalytic system may provide a direct approach to the synthesis of enantioselective diols from olefins. 

Ring expansion in conjunction with Tamao-type oxidation of carbon-silicon bonds provides access to 1,4-diols. The l-(l-iodoalkyl)-l-silacyclobutanes are available from 1-chlorosilacyclobutanes (addition of vinyl, Scheme 34) <1991TL6383>. The utility of silacyclopentanes formed by the ring expansion of SCB for the synthesis of diols has been reported <1992TL7031, 1995BCJ625>. 

Solladie, G. Applications of Chiral Sulfoxides in Enantioselective Synthesis of Diols and Total Synthesis of Natural Products, Enantiomer 1999, 4, 183-193. 

C. Dobler, G. M. Mehltretter, M. Beller, Atom-efficient oxidation of alkenes with molecular oxygen Synthesis of diols, Angew. Chem. Int. Ed. Engl. 38 (1999) 3026. 

Dehydrogenation of I -dibenzyloxytetrahydroarenes. In a recent synthesis of diol epoxides of carcinogenic arenes, Fu and Harvey found that 1,2-dibenzyloxytetra-hydroarenes are dehydrogenated in good yield by DDQ in refluxing dioxane. An example is formulated in equation (I). This method is superior to bromination-dehydrobromination the NBS route to 2 from 1 failed completely. 

Scheme 5.13. Os and W catalyzed synthesis of diols using H2O2 as the terminal oxidant.

The following questions relate to the synthesis of ( )-diol 4 from alkyne 1, shown below. [( ) indicates a racemic compound.]... 

Scheme 14.12 Enantioselective route to side chain 30, based on the LDH-PdOsW catalyzed synthesis of diol 27...

One recently reported synthesis of diols has been discussed earlier (Scheme 9). In a publication already mentioned in this Report on asymmetric syntheses based on chiral diamines containing a pyrrolidine ring, a synthesis of optically active diols (Scheme 28) from two consecutive Grignard additions to... 

Figure 7.2 Synthesis of diol cured polyurethane from monomeric diol and isocyanate terminated prepoiymer...

Formation of alkoxide complexes takes place on interaction of the most basic and the most acidic oxides/hydroxides with alcohols, due, most probably, to pro-tolytic catalysis. The most efficient turned to be in the synthesis of diol derivatives of the most acidic metal oxides - Re207 [115] and M0O3 [116] ... 

Scheme 13 Synthesis of diol-functionalized telechelic polymer through radical coupling reaction. Reprinted with permission from Yamago, S. Chem. Rev. 2009, 109, 5051. Copyright 2009 American Chemical Society.

Epoxides 1,2-Diols Synthesis of diols resolution of epoxides Epoxide hydrolase... 

Recently, the same group reported two different epoxide hydrolases from Sphin-gomonas sp. and Solatium tuberosum with distinct stereopreferences that enabled enantiodivergent synthesis of diols in excellent yields and selectivities (Scheme 9.12) [74]. 

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