1,2-Ethanediol, reaction with

Diols that bear two hydroxyl groups m a 1 2 or 1 3 relationship to each other yield cyclic acetals on reaction with either aldehydes or ketones The five membered cyclic acetals derived from ethylene glycol (12 ethanediol) are the most commonly encoun tered examples Often the position of equilibrium is made more favorable by removing the water formed m the reaction by azeotropic distillation with benzene or toluene... 

Z)-l-Methyl-2-butenylboronate 7 undergoes an exceptionally enantioselective reaction with benzaldehyde (99% ee), propanal (79%. 98% ee), 2-methyl-2-propenal (85%, 99% ee), and ( )-2-methyl-2-pentenal (81 %, 99% ee)10 38. Excellent enantioselectivity is also realized in reactions of the analogous chiral a-methyl-) y-disubstituted allylboronate27 40. Whether the l,2-dicyclohexyl-l,2-ethanediol auxiliary plays a beneficial role in this reaction, as suggested above for the asymmetric allylboration reactions of 6, has not yet been determined. 

Alkaline hydrolysis of the crude adduct formed with benzaldehyde, followed by treatment with diazomethane and column chromatography, affords methyl (2R,3S)-3-hydroxy-2-methyl-3-phenylpropanoate in 96% ee. Reduction of the crude products formed in the reactions with 2-inethylpropanal and 2,2-dimethylpropanal leads to the corresponding 1,3-diols with >96% ee. In both the hydrolysis and the reduction procedures, the chiral auxiliary reagent, 1,1,2-triphenyl-1,2-ethanediol, can be recovered and reused72. 

Direct conversion of the 6-sulfonates of D-galactopyranosides into their 6-deoxy-6-fluoro derivatives is usually hindered, because of the polar field-effect exerted by the lone electron pairs of the axial 0-4 (Ref. 158). Thus, the 6-0-mesylgalactoside 294 gave ° the 3,6-anhydro derivative 297 (23%) as the only isolated product on reaction with CsF in boiling ethanediol. How-... 

The cyclic phosphonate 41 was formed in the reaction of (/ )-l,l,2-triphenyl-1,2-ethanediol (40) with methanephosphonyl dichloride in a highly diastereoselective manner (dr=9 l) (Scheme 14) [31]. 

Scheme 14 Reaction of (R)-l,l,2-triphenyl-l,2-ethanediol (40) with methanephosphonyl dichloride...

Yamamoto and co-workers reported the use of scandium(lll) triflate as an esterification catalyst when acetic anhydride was used as the acetate source.5 6 While they only reported on monoalcohols (1°, 2°, and 3°) on a small scale, the submitters modified the Yamamoto procedure to suit the submitters reaction with the 1,1,2-triphenyl-1,2-ethanediol. As detailed above, the current procedure provides a yield of the HYTRA acetate that is comparable to the procedure reported by Braun and coworkers,2 1 but via simple, direct filtration for the reaction mixture. 

P-Hydroxy carboxylic acids (12,3).2 This acetate on double deprotonation with LDA undergoes diastereoselective aldol reactions with aldehydes. The adducts are easily hydrolyzed to optically active P-hydroxycarboxylic acids with release of (R)-(+)-1,1,2-triphenyl-1,2-ethanediol, the precursor to 1. Optically pure acids can be obtained by crystallization of the salt with an optically active amine such as (S)-(—)-1 -pheny lethylamine. 

Aldehydes and ketones are usually protected by converting them to acetals by reaction with an alcohol in the presence of acid (see Section 18.9). Although many different alcohols could be used, ethylene glycol (1,2-ethanediol) or 1,3-propanediol is most often... 

Wittig salt (51). Wittig reaction with the C14 dialdehyde (52) gave racemic (27). The 3-hydroxy-p-ring system was also obtained from a-ionone (53). Oxidation with t-butyl chromate gave the ketone (54), which with ethanediol underwent double-bond migration to give (55), which was hydrolysed in the presence of... 

Styrylboronic ester 24 was subjected to the catalytic hydroboration with cat-echolborane in the presence of rhodium complexes coordinated with chiral bis-phosphine ligands. Oxidation of the resulting 1,2-diboryl product 25 gave optically active 1-phenyl-1,2-ethanediol (26) (Scheme 6) [26]. The reaction with BINAP (7) at -60 °C gave (S)-diol 26 of over 70% ee. 

The highly reactive TT-bond of an indole nucleus can be protected by the addition of an ethylenedioxy unit. The adducts are formed in a reaction with ethanediol in the presence of PhI(OCOCF3)2. Reversion of the process is accomplished by NaBH3CN. ... 

ETHANEDIOL (107-21-1) C HsO Combustible liquid [explosion limits in air (vol %) 3.2 to uel unknown flash point 231°F/111°C autoignition temp 775°F/413°C Fire Rating 1]. Violent reaction with oxidizers and oxidizing acids, sulfuric acid. Forms explosive mixture with sodium perchlorate. Incompatible with strong acids, caustics, aliphatic amines, isocyanates, chlorosulfonic acid, oleum, potassium bichromate, phosphorus pentasulflde, sodium chlorite. On small fires, use dry chemical powder (such as Pmple-K-Powder), alcohol-resistant foam, or COj extinguishers. 

Subsequently readily available cholesterol has been degraded microbiologically to androst-1,4-diene-3,17-dione which is then ketalised with ethanediol to form regiospecifaically the 3-ketal, aromatisation of which occurs upon mild reaction with lithium in THF containing diphenyl/diphenylmethane Reaction takes place by way of the radical anion obtained from the lihium and diphenyl and diphenylmethane quenches the methyllithium arising from the leaving angular... 

Bt) group in organic synthesis and synthetic methodology. This group also adapted the methodology for a novel preparation of 5-(aroylamino)-2-aryloxazoles 587 (Scheme 1.160). Reaction of l,2-bis(17f-benzotriazol-l-yl)-l,2-ethanediol 583 with two equivalents of an aryl amide affords a l,2-(diaroylamino)-l,2-di(benzo-triazol-l-yl)ethane, 584 in excellent yield. Heating 584 with sodium hydride in... 

An interesting aspect of lER catalysis is that the course of reaction with a homogeneous catalyst can be altered in the presence of lER. An example of this is the mono-acylation of diols ranging from 1,3-ethanediol to 1,16-hexa-decan-ediol by transesterification in ester-solvent mixtures catalyzed by an acidic lER (reaction 6.26) (Takeshi et al., 1994). 

TmsCN. Treatment of l,2-0-isopropylidene-3,5-di-0-mesyl-6-0-trityl-D-glu-cose with ethanediol and TsOH gives the C-formyl compound 161 in 53% yield from which (+)-muscarine iodide 162 and its epimer at the alcohol centre were made. Compounds 163 and 164 have been made from 2-deoxy-D-ribose donors by reaction with a benzyl Grignard reagent and allyltrimethylsilane, respectively, in the key steps. The products were incorporated into oligonucleotides during a study of the interactions of DNA with peptides. ... 

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