Corey-Winter synthesis

Oxanorbornadiene (2). This hydrocarbon has been obtained from (1) by the modified Corey-Winter synthesis (5, 661). Some interesting reactions of... 

The Corey-Winter synthesis has proved useful for the generation of a large number of structurally interesting alkenes, including some unstable alkenes that must be captured in situ (eq 2). ... 

COREY - WINTER Alkene synthesis Alkene synthesis from glycols via cyclic t, 2-lhionocartx)nates... 

As expected, the yields of catenanes by this approach are low, which is why improved methods for the preparation of such compounds have been developed. The acyloins are often only intermediate products in a multistep synthesis. For example they can be further transformed into olefins by application of the Corey-Winter fragmentation. 

The Corey-Winter reaction provides a useful method for the preparation of olefins that are not accessible by other routes. For instance it may be used for the synthesis of sterically crowded targets, since the initial attack of phosphorus at the sulfur takes place quite distantly from sterically demanding groups that might be present in the substrate molecule. Moreover the required vicinal diols are easily accessible, e.g. by the carbon-carbon bond forming acyloin ester condensation followed by a reductive step. By such a route the twistene 10 has been synthesized ... 

The Corey-Winter olefin synthesis is based on the stereospecific loss of carbon dioxide or carbon disulfide from the carbenes formed by treatment with bivalent organophosphorus compounds of thionocarbonates or trithiocarbonates [218-220]. 

The preparation of 4-alkenyl (3-lactams (II, Fig. 9) has been reported through either Homer-type olefination of a common 4-formyl (3-lactam or the Corey-Winter alkene synthesis applied to 4-dihydroxyalkyl (3-lactams [263]. 

Alkenes from 1,2-diols (7, 385-386). An efficient synthesis of (S)-(—)-y-methoxymethyl-a, /J-butenolide (3) from (+)-5-0-methyl-D-ribonolactone (1) involves conversion to the cyclic orthoformate 2 followed by pyrolysis to give 3 in 66.5% overall yield.1 In this case, the Corey-Winter reaction and the Hanessian route (8,192) were... 

Corey-Winter olefin synthesis. The Corey-Winter olefin synthesis (1, 1233-1234) involves treatment of a thionocarbonale with trimethyl phosphite ... 

Corey-Winter olefin synthesis (I. I23.3-I234). Chong and Wiseman were able to demonstrate the transient existence of bicyclo[3.2.l]octenc-l (2, a bridgehead alkene which violates Bredt s rule) by application of the Corey-Winter olefin synthesis. Thus treatment of the thionocarbonatc (I) with triethyl phosphite at reflux (165°) fur 24 hr. in the presence of I,3-diphenyli obenzofurane (1, 342-343 2, 178-179) leads to the formation of two Diels-Alder adducts (3) and (4) derived from (2). 

The enantiospecific synthesis of naturally occurring cyclohexane epoxides such as (+)-crotepoxide and (+)-boesenoxide was accomplished by T.K.M. Shing et al. The key Intermediate 1,3-cyclohexadlene was prepared using the Corey-Winter protocol on a c/s-vicinal diol. The resulting diene was then converted to the natural product after several steps. 

The absolute configuration of radiosumin, a novel potent trypsin inhibitory dipeptide, was determined by T. Shioiri and co-workers by carrying out the first enantioselective total synthesis of the natural product. The s-trans 1,3-diene in one of the key synthetic intermediates was installed by the Corey-Winter olefination using the Corey-Hopkins reagent (1,3-dimethyl-2-phenyl-1,3,2-diazaphospholidine). 

G.W.J. Fleet and co-workers synthesized L-(+)-swainsonine and other more highly oxygenated monocyclic structures that exhibited inhibitory activity toward naringinase (L-rhamnosidase). In order to remove a c/s-vicinal diol moiety in the endgame of the synthesis, the Corey-Winter olefination was utilized. 

Horton, D., Tindall, C. G., Jr. Synthesis and reactions of unsaturated sugars. XI. Evidence for a carbenoid intermediate in the Corey-Winter alkene synthesis. J. Org. Chem. 1970, 35, 3558-3559. 

The Corey-Winter reaction is a valuable route for the synthesis of unsaturated sugars and complex cycloalkenes. Alkenes may also be obtained by pyrolysis of methyl xanthates... 

Corey-Winter olefin synthesis. Synthesis of olefins from 1,2-diols and thiocarbonyldiimidazole. Treatment of the intermediate cychc thionocarbo-nate with trimethylphosphite yields the olefin by els elimination. 

Crich, D. Pavlovich, A.B. Wink, D.J. Synthesis of fully-substituted enediynes by the Corey-Winter reaction. Synth. Commun. 1999, 29, 359-377. 

Alkene synthesis from glycols via cyclic 1,2-thionocarbonates (Corey-Winter) or 1,3-dioxolanes (Eastwood) (see 1st edition). 

The Corey-Winter olefin synthesis is a two-step transformation of a diol 1 to an olefin 3.1"3 A cyclic thionocarbonate 2 is prepared from the diol 1, and subsequent heating of 2 with phosphite affords olefin 3. 

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