3-Buten-l,2-diol

An early attempt to hydroformylate butenediol using a cobalt carbonyl catalyst gave tetrahydro-2-furanmethanol (95), presumably by aHybc rearrangement to 3-butene-l,2-diol before hydroformylation. Later, hydroformylation of butenediol diacetate with a rhodium complex as catalyst gave the acetate of 3-formyl-3-buten-l-ol (96). Hydrogenation in such a system gave 2-methyl-1,4-butanediol (97). 

Heating with cuprous chloride in aqueous hydrochloric acid isomerizes 2-butene-l,4-diol to 3-butene-l,2-diol (98)] Various hydrogen-transfer catalysts isomerize it to 4-hydroxybutyraldehyde [25714-71-0] (99), acetals of which are found as impurities in commercial butanediol and... 

Treatment with acidic catalysts dehydrates i j -butenediol to 2,5-dihydrofuran [1708-29-8], C H O (100). Cupric (101) or mercuric (102) salts give 2,5-divinyl-l,4-dioxane [21485-51-8], presumably via 3-butene-l,2-diol. 

Some additional examples, where the stereochemical outcome of the cycloaddition to chiral alkenes has been explained in terms of the Honk—Jager model, should also be mentioned. The diastereomer ratio found in the reaction of y-oxy-a,p-unsamrated sulfones (166), with Morita-Baylis-Hillman adducts [i.e., ot-(a -hydro-xyalkyl)-acrylates (167)] (Scheme 6.27), with dispiroketal-protected 3-butene-l,2-diol (168), and with a,p-unsamrated carbonyl sugar and sugar nitroolefin (169) derivatives, all agree well with this model. 

Dihydromuscimol (49) is a conformationally restricted analogue of the physiologically important neurotransmitter y-aminobutyric acid (GABA) and has been prepared using the cycloaddition of dibromoformaldoxime to A-Boc-allylamine followed by N-deprotection with sodium hydroxide (Scheme 6.52) (278). The individual enantiomers of dihydromuscimol were obtained by reaction of the bromonitrile oxide with (5)-( + )-l,2-0-isopropylidene-3-butene-l,2-diol, followed by separation of the diastereoisomeric mixture (erythro/threo 76 24), hydrolysis of respective isomers, and transformation of the glycol moiety into an amino group (279). 

Kemper, R.A. Elfarra, A.A. (1996) Oxidation of 3-butene-l,2-diol by alcohol dehydrogenase. Chem. Res. Toxicol., 9, 1127-1134... 

Krause. R.J.. Sharer, J.E. Elfarra, A.A. (1997) Epoxide hydrolase-dependent metabolism of butadiene monoxide to 3-butene-l,2-diol in mouse, rat, and human liver. DrugMetab. Disp., 25.1013-1015... 

Acid-catalyzed hydrolysis of isobutylene oxide (8) is >750 times faster than that of ethylene oxide (6), and > 99% of the glycol product is from addition of solvent at the tertiary carbon.23 These results are consistent with a mechanism in which there is significant positive charge on the tertiary carbon at the transition state, as discussed in the previous section. Butadiene monoepoxide (10) is slightly less reactive than isobutylene oxide,36 and its acid-catalyzed hydrolysis can potentially proceed via a resonance-stabilized allyl cation (Scheme 6). However, the acid-catalyzed hydrolysis of 10 yields 96% of 3-buten-l,2-diol (15) and only 4% of 2-butene-1,4-diol (16),36 and the acid-catalyzed methanolysis of 10 is reported to yield only 2-methoxy-3-buten-l-ol.37 An A-2 mechanism proceeding via transition state 17 may account for the observation that 1,2-diol 15 is the predominant product from acid-catalyzed hydrolysis of 10. The minor yield of the 1,4-diol 16 may be formed from reaction of... 

The addition of (ethoxycaibonyl)formonitrile oxide to (+)-(S)-isopropylidene-3-butene-l,2-diol led to an 80 20 mixture (60% diastereomeric excess) of diastereomers in ca. 70% yield (Scheme 21) the major... 

CXir synthesis of (R)-(-)-mevalolactone (24) is shown in Scheme 10. The crucial intermediate, synthesized by the earlier described method, is (+)-2-methyl-3-butene-l,2-diol, Its... 

VEC Hydrolysis. 0.2 M NaOAc and 0.2 M HOAc solutions were mixed to yield a buffer solution with pH of 4.03. 75 ml of this solution was placed in a 100 ml 3-necked flask equipped with a magnetic stirrer, condenser, heating mantle and thermometer. 1.5 ml of VEC was added to the solution. The solution was heated at 80°C for four hours with stirring then cooled to room temperature and analyzed for 3-butene-l,2-diol by gas chromatography. 

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