1,2-diol substituted with

There have been a number of different synthetic approaches to substituted PTV derivatives proposed in the last decade. Almost all focus on the aromatic ring as the site for substitution. Some effort has been made to apply the traditional base-catalyzed dehydrohalogenation route to PTV and its substituted analogs. The methodology, however, is not as successful for PTV as it is for PPV and its derivatives because of the great tendency for the poly(u-chloro thiophene) precursor spontaneously to eliminate at room temperature. Swager and co-workers attempted this route to synthesize a PTV derivative substituted with a crown ether with potential applications as a sensory material (Scheme 1-26) [123]. The synthesis employs a Fager condensation [124] in its initial step to yield diol 78. Treatment with a ditosylate yields a crown ether-functionalized thiophene diester 79. This may be elaborated to dichloride 81, but pure material could not be isolated and the dichloride monomer had to be polymerized in situ. The polymer isolated... 

Generally, oxepins have a tendency to contract to a six-membered carbocycle when treated with acid. The driving force is the aromaticity of the phenol formed. However, when the less stable cyclohexa-2,5-diene-1,4-diol with an appropriate substitution pattern is treated with acid, the oxepin system is obtained. The treatment of cyclohexadienediols that are substituted with tert-butyl groups in the 2- and 6-positions and aryl at Cl and C4 with trifluoroacetic acid produces oxepins 1 with elimination of water.186 187 This reaction, however, is restricted to certain aryl substituents with at least some electron-donating effect. Generally, cyclohexa-2,4-dienone derivatives 2 are formed.187,188... 

The lithium 2-butenyl(triethyl)aluminate complex, prepared in situ from 2-butenyllithium and triethylaluminum, displayed poor diastereoselectivity in a reaction with benzaldehyde (anti/syn 56 44)7. (Z)-3-Alkoxy-substituted aluminate complexes such as A-C, however, give good diastereoselectivity in aldehyde addition reactions8. The reactions of A with aldehydes at —100 °C give the jyw-diol monoether with >95% diastereoselectivity and >80-95% regiose-... 

Polymer-attached 1,3-diols react with substituted benzaldehyde dimethylacetals in the presence of MesSiCl 14 to give 1,3-dioxanes in high yields [30]. 

The applicability of axially chiral 1, l -binaphthalcnc-8,8 -diol in asymmetric Diels-Al-der reactions was studied by Fuji and colleagues190. They studied the Lewis acid catalyzed reaction of the unsymmetrically substituted maleate ester of 1,1 -binaphthalene-8,8 diol 302 with cyclopentadiene. The diastereoselectivity proved to depend strongly on the Lewis... 

It should be noted that one of these diols, the hydroquinone, did not provide any oligomer in the first step. This was due to the formation of the quinone structure which made it impossible to use hydroquinone directly in the substitution reaction. An alternate method was used to overcome this problem which involved the use of 4-methoxyphenol to obtain the sulfone product, followed by cleavage of the methyl ether to the diol (VIII) with boron tribromide. This set of reactions is outlined in Figure 5. 

Incorporation Into a co- or terpolymer of a d1ol containing monomer such as solketal acrylate (SA, H, a comonomer readily hydrolyzed by aqueous add to a diol) likewise Increases crosslinking (Scheme 4). Such polymers exhibit Improved dry, wet and solvent resistance (Table V). Alternatively, half of the ABDA comonomer can be substituted with SA, without significantly degrading properties vs the Initial ABDA only sample. 

An interesting application of unsaturated diols 460 is the preparation of substituted perhydrofurofurans 463, a heterobicyclic core, present in families of naturally occurring products, such as aflatoxines ° . Hydroboration of diols 460 with BH3 in THE at 0°C... 

Dodecafluoro(2,3-dimethylbutane-2,3-diol) reacts with sulfur tetrafluoride in an unconventional way instead of replacement of the hydroxy groups by fluorine, the substitution of four fluorine atoms in the sulfur tetrafluoride molecule by oxygen occurs to give a good yield of perfluorinated spiro-A4-sulfane 8.62... 

In a similar way, dinitro-4-azaheptane-l,7-diols reacted with phenyl-boronic acid to yield isomeric cis- and trans-substituted diptychs with condensed 5-nitrotetrahydro-2,l,3-boraoxazine rings (5)38,37 [Eq. (2)]. 

Included in this class of olefins is ( )-stilbene (entry 20), which throughout studies of AD has usually been the olefin dihydroxylated with the highest degree of enantioselectivity. Availability of (R,R) or (.5,5)-1,2-diphenyl-1,2-ethanediol (also referred to as stilbenediol or dihydrobenzoin) with high enantiomeric purities has led to reports of a number of applications, including incorporation into chiral dioxaphospholanes [50], chiral boronates [51], chiral ketene acetals [52], chiral crown ethers [53], and conversion into 1,2-diphenylethane-1,2-diamines [54]. Dihydroxylation of the substituted rran.r-stilbene 46 with Os04/NMO and DHQD-CLB gives the i ,/ -diol 47 with 82% ee in 88% yield [55]. 

Sharpless asymmetric dihydroxylation of simple allylsilanes yields the corresponding diols 182 with moderate enantioselectivity (equation 154)273. However, when 183 is treated under similar conditions, substituted /-lactones 184a and 184b are obtained in high diastereo- and enantioselectivities (equation 155)274-277. 

Arylsulfonylmethyl-substituted dinaphthodioxepins 223 were obtained from arylsulfonylalkynes via Michael reaction. The procedure engages NaH-supported reaction of 1,1 -binaphthalene-2,2 -diol 222 with 220 (Ar = phenyl, tolyl). The procedure can also be performed using (Z)- or (ft)-l-chloro-2-phenylsulfonylethylene and bis(phenylsulfonyl)ethylene, respectively, instead of arylsulfonylalkynes (Scheme 64) <1996SL1481>. 

The incorporation of cyclic substituents, such as propane-1,3-diyldioxy, its ethyl and benzyl derivatives substituted at the (1-thiophene carbons of 21,23-dithiaporphyrins 240b and 21-monothiaporphyrins 241b (Scheme 95), has also been reported (04BCJ1173) by condensing the substituted thiophene diols 239b with benzaldehyde and pyrrole. The cyclic substituents at the (5-thiophene carbon atoms alter electronic properties of porphyrin. 

To develop new methods for organic synthesis, Woerpel and coworkers exploited the inherent reactivity of di -fc/ f-butylsilacyclopropanes to create new carbon-carbon bonds in a stereoselective fashion (Scheme 7.7).62 They discovered that transition metal salts catalyze the insertion of carbonyl compounds into the strained carbon-silicon bond to form oxasilacyclopentanes. The regioselectivity of insertion could be controlled by the identity of the catalyst. Copper promoted the insertion of croto-naldehyde into the more substituted C-Si bond of 52 to afford oxasilacyclopentane 53,63 whereas zinc catalyzed the insertion of butyraldehyde into the less substituted bond of 52 to provide the complementary product, 54.64 Oxasilacyclopentanes (e.g., 55) could be transformed into useful synthetic intermediates through oxidation of the C-Si bond,65 66 which provided diol 56 with three contiguous stereocenters. 

Phthalocyanines 84 and 85 substituted with six optically active alkyl chains and one chiral diol have been synthesized by mixed cyclization of the two corresponding phthalonitriles [72], The self-organizing properties of these compounds in chloroform solution and thin film have been studied by a range of spectroscopic and physical methods. Both compounds show split Q-band absorptions at 678 and 694 nm in chloroform, and the emission (at 696 nm) is red-shifted compared with that of a non-diol-containing analog. Upon addition of 0.5% methanol, the absorption at 694 nm... 

Acetalization of l-alkenes. The Wacker uinversion of l-alkenes to methyl ketones by oxidation catalyzed by PdCE-CuCl takes a different course when applied to vinyl ketones (1). Thus oxygenation of mixtures of I and 1,3- or 1,2-diols catalyzed by PdCE-CuCl results in cyclic acetals formed by exclusive attaek at the terminal carbon atom. A similar reaction occurs with l-alkenes substituted with COOCH,. 

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