Frans-Glycols

When 2,3-diphenylindenone (188) is treated with potassium hydroxide in alcohol, 138 is formed in various yields, depending on the alcohol employed (isopropanol 51% ethanol 44% methanol 2%) besides the /1-alkoxy-ketone 189, the fran. -glycol 190 (mp 233-235°C, 232-236°C ) and... 

Monoperoxysuccinic acid frans-Glycols from ethylene derivatives s. 19,192... 

The new recycling concept was apphed to several C - C bond-forming reactions, for example, to the telomerization of butadiene with ethylene glycol or carbon dioxide, to the isomerizing hydroformylation of frans-4-octene and to the hydroamino-methylation of 1-octene with morpholine. 

Methylenebis(oxy) ]bis(2-chloroformaldehyde), see Bis (2-chloroethoxy) methane Methylene chlorobromide, see Bromochloromethane Methylene dichloride, see Methylene chloride Methylene dimethyl ether, see Methylal Methyl 2,2-divinyl ketone, see Mesityl oxide Methylene glycol, see Formaldehyde Methylene glycol dimethyl ether, see Methylal Methylene oxide, see Formaldehyde Methyl ethanoate, see Methyl acetate (1 -Methylethenyl)benzene, see a-Methylstyrene Methyl ethoxol, see Methyl cellosolve 1-Methylethylamine, see Isopropylamine (l-Methylethyl)benzene, see Isopropylbenzene Methylethyl carbinol, see sec-Bntyl alcohol Methyl ethylene oxide, see Propylene oxide ds-Methylethyl ethylene, see cis-2-Pentene frans-Methylethyl ethylene, see frans-2-Pentene Methyl ethyl ketone, see 2-Bntanone Methylethylmethane, see Butane... 

Problem 6.34 ( ) Describe the stereochemistry of glycol formation with peroxyformic acid (HCO,H) if cw-2-butene gives a racemic glycol and frans-2-butene gives the meso form. (6) Give a mechanism for cis. 

A number of frans-[0s(0)2(py)2L] complexes (H2L = glycolic, 2-hydroxyisobutyric, (S)-(+)-mandelic, or 2-salicylic acid) have been prepared from [0s(0)2(0Me)4]2 and py with the ligand. They have been characterized by IR, mass, and NMR ( H and 13C) spectroscopies (408) and X-ray structures for L = glycolate(2-) and salicylate (401, 402). The Os(V) complex, (PPh4)[0s(0)(ehba)2] has been prepared from the reaction of the ligand with (PPh4)[0s04] and has been characterized by IR spectroscopy (23a). 

An epoxide is formed from alkene and peroxymethanoic acid (H202 -l- HC02H) but is cleaved by the HC02H present to a frans-diol. Alternatively, osmium tetroxide may be used in fe/t-butyl alcohol and leads to the c/ s-diol. Potassium permanganate in neutral can be useful for preparation of c/ s-glycols. (See Section 11-70.)... 

The achiral triene chain of (c//-frans-)-3-demethyl-famesic ester as well as its (6-cir-)-isomer cyclize in the presence of acids to give the decalol derivative with four chiral centres whose relative configuration is well defined (P.A. Stadler, 1957 A. Eschenmoser, 1959 W.S. Johnson, 1968,1976). A monocyclic diene is formed as an intermediate (G. Stork, 1955). With more complicated 1,5-polyenes, such as squalene, oily mixtures of various cycliz-ation products are obtained. The 18,19-glycol of squalene 2,3-oxide, however, cyclized in modest yield with picric add catalysis to give a complex tetracyclic natural product with nine chiral centres. Picric acid acts as a protic acid of medium strength whose conjugated base is non-nucleophilic. Such adds activate oxygen functions selectively (K.B. Sharpless, 1970). 

Stereochemical studies have shown that the hydration of epoxides (of cyclic olefins as well as arenes) is performed by epoxide hydrolase in such a way that irans-diols are formed. Aliphatic epoxides have also been shown to undergo frans-hydration, which means that frons-epoxides yield erythm-glycols and ds-epoxides result in f/jreo-glycols (Hammock et al., 1980). 

This subject has recently been reviewed. Several additional papers have appeared on the catalytic oxidation of alkenes by O2 in the presence of PdCl(MeCN)2N02(148). Terminal alkenes and frans-cyclooctene yield the corresponding ketones, cyclopentene and cyclohexene the corresponding allyl alcohol, and bicyclic alkenes the corresponding epoxide. Heterometallacy-clopentanes such as U52) have been isolated from the reaction of (148) with norbornene (dicy-clopentadiene), and characterized by X-ray crystallography. Glycol monoacetates were obtained from the reaction of (148) with terminal alkenes in acetic acid. ... 

Epoxides are cleaved by treatment with acid just as other ethers are, but under much milder conditions because of ring strain. As we saw in Section 7.8, dilute aqueous acid at room temperature is sufficient to cause the hydrolysis of epoxides to 1,2-diols, also called vicinal glycols. (The word vicimil means "adjacent," and. a glycol is a diol.) The epoxide cleavage takes place by S -like backside attack of a nucleophile on the protonated epoxide, giving a frans-l,2-diol as product. 

The hydrolysis rate of poly (ortho esters) can be further manipulated by a combination of hydrophilicity and the use of diols that contain a pendant carboxylic acid, such as 9,10-dihydroxystearic acid [36]. Figure 16 shows the release of a marker compound p-nitroacetanilide from a hydrophobic matrix prepared from a 60/40 mole ratio of frans-cyclohexanedimethanol and 1,6-hexanediol containing varying amounts of 9,10-dihydroxystearic acid. While there is a noticeable effect, it is relatively minor. However, when the hydrophilicity of the matrix is increased by using a 60/10/30 mole ratio of trans-cyclohexanedimethanol, 1,6-hexanediol and triethylene glycol, the effect of 9,10-dihydroxystearic acid is greatly magnified, as shown in Fig. 17. 

The separation of deuterated butenes gave the following relative retention times (relative to the non-deuterated) cis-1-butene-1-dj, 1.036 frans-l-butene-l-dj, 1.027. It can be seen that the use of a solution of silver nitrate in ethylene glycol enables good separations of deuterated olefins to be achieved. Unfortunately, the separation time is long (about 5 h), but can probably be reduced by the use of more efficient capillary columns and optimization of the separation conditions in particular, as the separation temperature is decreased the selectivity increases sharply. 

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