Other Unsaturated Derivatives

In the series of furanoid 3,4-unsaturated compounds the well known 3-deoxy-1,2 5,6-di-0-isopropylidene-a -D-eryr/iro-hex-3-enofuranose is obtained when the trifluoromethanesulphonate of 1,2 5,6-di-O-isopropylidene-a-D-glucose is treated with strong bases. It was resistant to reaction with ammonia. An alternative, suitable means of preparing such alkenes involves the treatment of tosylhydrazones of keto-compounds with sodium acetate in DMF which is a 

A novel type of C=C linked disaccharide derivative (34) has been produced in good yield by condensation of a phosphorus ylide derived from 6-deoxy-6-iodo-1,2 3,4-di-0-isopropylidene-o -D-galactopyranose with the aldehyde corresponding to the furanoid moiety. Likewise, an alkene was obtained using this 

In the area of 6,7-unsaturated pyranoid derivatives compounds (43) (E,Z isomeric mixtures) have been made in Tronchet s laboratory and are of potential value for the synthesis of derivatives of lincomycin. The related methyl compound (44) (Z-isomer) has been used to obtain compounds with epoxypropyl side-chains related to the antibiotic asperlin.  

study of methyl 4,6-O-benzylidene-ct- and - -Yi-erythro-heitrl-enopyranoside is mentioned in Chapter 20. Iron carbonyl complexes of sugar enones are described in Chapter 16. 

Overend s group has described the synthesis and reactions of some 2- and 3-arylazo-derivatives of methyl 2,3-dideoxy-D-pent-2-enofuranoside [e.g. (224)— (228)]. These arylazoalkenes (Ar = Ph or /j-NOaCgH,) are useful synthetic 

Mochalin and A. N. Kornilov, Khim. geterotsikl. Soedinenii, 1975, 171 (Chem. Abs., 

The thermal degradation of 6-5 -allyl and 6-S-benzyl dithiocarbonates derived from methyl cellobioside, sucrose, and cellulose has yielded such unsaturated sugars as (237) with juxtaposed double bonds.  

Wittig methylenation of the keto-sugar (238) gave the unsaturated derivatives (239) and (240) in addition to the expected product (241). l,2 5,6-Di-0-isopropylidene-a-D-r/Z o- and -x /o-hexofuranos-S-uloses reacted with stabilized 

The stereoselectivity of nucleophilic additions to the nitro-olefin (245) has been shown to be influenced more by the solvent and temperature than by the type of substituent at 0-3.  

Otherwise, unsaturation may be introduced by use of carbonyl-containing carbohydrate derivatives and carbon nucleophiles that contain alkene (or, if desired, alkyne) functionality, a notable illustration being the tin-or indium-mediated C-l allylation of unprotected sugars. As an illustration, D-arabinose, treated with allyl bromide in aqueous ethanol in the presence of tin gives, after acetylation, 278 in 85% yield.258 In this procedure aldoses react better than do ketoses, and pentoses better than hexoses. More usual is the use of Grignard reactions to give, for example, the octynes 279. 

Very frequently, Wittig and Grignard reactions are applied to the relevant ketones to generate the branch points in compounds such as 280 and 281.259 

Two oligosaccharides from Marsdenia roylei, Phytochemistry, 50 (1999) 1353-1357. 

Ferrier, Unsaturated sugars, Adv. Carbohydr. Chem. Biochem., 24 (1969) 199-266. 

Ferrier, Monosaccharides and their derivatives, in M. F. Ansell (Ed.), Rodd s Chemistry of Carbon Compounds, Supplement to 2nd edition, Vol. 1F,G, Elsevier, Amsterdam, 1983, pp. 19-218. 

Praser-Reid has provided a sequel to his 10 year old review of some unsaturated derivatives, and has stressed the usefulness of 2,3- 

The unsaturated lactones (13) are obtainable directly from the corresponding 2,3-unsaturated ethyl a-glycosides by treatment with pyridinium chlorochromate in the presence of acid resin or with Jones reagent.Treatment of 2,4,6-tri- -benzyl-3- -tosyl-D- 

Methyl 2,3. -trldeoxy-6.7-0-lsopropylldene-D-erythro-hept-2-enopyranoside was converted into 4-deoxy-D-allo-, -D-manno-. 

In the area of 6-deoxyhexopyranosyl derivatives, N-(phenyl-selenyDphthalimide has been used to effect elimination from the 

6-hydroxy compound to give alkene (20), and the same reagent allowed access to the related unsaturated sugar (21) from the acyclic alkene (22) (obtained using a Wittig reaction) by an 

Praser-Reld has reviewed his more recent developmental work using 2,3-unsaturated carbohydrate derivatives.  

The effects of pressure, temperature and solvent on asymmetric induction in the [4+2]cycloaddition reaction of 2,3- -isopropyliciene 

The four diastereomers were produced equilibration favours the 

Several 2,3-unsaturated compounds bearing substituents at C-3 are mentioned elsewhere (Chapters 8 and 111). 

Reagents i, MeO(F)C C(SOPh)CHjCH20Me-KH U., TsOCH=CHCHO - NoiH , iu, MeOCH PPh iv, eraAtcu Ph3p 

New methods of introducing double bonds into sugar rings continue to appear, and this year 3-methyl-2-selenoxo-l,3-benzothiazole applied to epoxides is advocated. In dichloromethane and in the presence of trifluoroacetic acid it gives the alkenes in high yield.Otherwise, potassium iodide, zinc, and phosphorus pentoxide in DMF at 90 °C can be used effectively, methyl 2,3- 

Spectra of 22 racemic methyl 3,4-dideoxyald-3-enopyranosides have been recorded, and from the data acquired conformational equilibria were estimated. For the pentose members (22) and (23) of the series the preferred conformations are the half-chairs with the anomeric groups held axial by the anomeric effect.  

An extension of the reaction of Bernet and Vasella (see Vol. 13, p. 122) by which fully protected 6-bromo-6-deoxyhexopyranosides are converted into acyclic aldehydic 5,6-dideoxyhex-5-enoses involves conversion of unsubstituted methyl 6-bromo-6-deoxyhexopyranosides into the corresponding 5,6-unsatur- 

Other examples have been given of the preparation of branched-chain and extended-chain alkenes by application of Wittig reagents to sugar aldehydes and ketones,and the mass spectra of alkenes derived from 1,2 5,6-di-O-iso-propylidene-D-r/Z o-hexos-3-ulose have been described.Compound (25) was 

Reagents i, Ph3P=CH2i ii, CHjNO iii, ACjO-DMSO iv, NaBH, v, H vi, Brj-HOAc vii, RSH 

Oxidation of methyl 2,3,6-tri-O-benzoyl-a-D-galactopyranoside with DMSO-acetic anhydride yielded mainly the enolone (336 R = OBz), owing to the tendency of the initially formed hexopyranosid-4-ulose to eliminate benzoic acid. The enolone (336 R = OBz) yielded the hydroxymaltol derivative (337) or (338) when treated with acetic acid-sodium acetate or with trifluoroacetic acid, respectively. Mechanisms for the conversions (336) - (337) and (338) were proposed on the 

6-methoxy-2i/-pyran-3(6/f)-one and its 2-methyl derivative from furfuryl alcohols.  

The elimination of hydrogen bromide from methyl 2-0-benzoyl-3-bromo-3,6-dideoxy-4-O-methyl-a-L-altropyranoside (168) under azidolysis conditions to give the 3,4-unsaturated sugar azide (169), etc., has been referred to in Chapter 8. 

Hayashi, N. Takeda, H. Saeki, and E. Ohki, Chem. and Pharm. Bull, (.fapanj, 1977, 25, 2134. 

Two new metabolites, virescenosides D and H, isolated from the fungus Acre-monium luzulae (Fuckel) Gams have been identified, on the basis of chemical and spectroscopic evidence, as the 4,5-unsaturated glycosides (349) and (350X respectively. Two other metabolites, virescenosides E and L, isolated from this fungus differ from (349) and (350) in the nature of the aglycone (virescenol A instead of virescenol B). Enantiomeric forms of 9-(5-deoxy-p-eryt/iro-pent-4-enofurano-syl)adenine have been synthesized by way of dehydroiodination of appropriately protected 5 -deoxy-5 -iodo-nucleosides with DBU in DMF. °  

Treatment of the product of periodate oxidation of methyl 4,6-0-benzylidene-a-D-glucopyranoside with p-toluenesulphonylhydrazine then with sodium borohydride in ethanol gave an iV-toluene-p-sulphonyl-2,3-epimine which on K. Heyns and R. Hohlweg, Chem. Ber., 1978, 111, 1632. 

Preparation of the 3,4-unsaturated anhydro-sugar (16) was effected from 

Condensation between the alkenes (27), which were prepared by standard methods from o-allose, and 6-benzamidochloromercuripurine gave access to the nucleoside (28), the enantiomer of which was synthesized similarly from D-talose.  

Several alkynes related to compound (29) were prepared by treatment of the corresponding dialdose derivative with alkynyl Grignard reagents, and by reduction and oxidation processes they were converted into a series of octose derivatives, e.g. reduction gave 7,8-dideoxy compounds and oxidation alkynyl glycos-6-uloses.  

An acyclic unsaturated compound used in the synthesis of 2-deoxypentoses is noted in Chapter 11. 

The preparation of methyl 4,6-0-benzylidene-2,3-dideoxy-j8-D-e/ //[ro-hex-2-enopyranoside from the 2,3-disulphonates (84) using the Tipson-Cohen reaction has been noted in Chapter 6.  

Racemic methyl 2,3,6-trideoxy-a- or -j8-hex-2-enopyranoside (231) reacted with phthalimide, triphenylphosphine, and diethyl azodicarboxylate to give 4-deoxy-4-phthalimido-derivatives, e.g. (232), having the configuration at C-4 inverted. However, products arising from both direct and allylic substitution 

Banaszek, B. Szechner, J. Mieczkowski, and A. Zamojski, Roczniki Ghent., 1976, 50, 105. 

6-0-benzoyI-4-iodo-2,3,4-trideoxy-Q -D-///r o-hex-2-enopyranoside have been resolved following determination of the crystal structure, which showed that the six-membered ring adopts a half-chair conformation.  

Photolysis of various aryl-substituted 6-esters of l,2 3,4-di-0-isopropylidene-a-D-galactopyranose (240) yielded a mixture of 6-deoxy-l,2 3,4-di-(9-iso-propylidene-a-D-galactopyranose (0—50%) and the terminal alkene (241) (0—26%). Sucrose-5- (242) and -5 -enes (243) have been synthesized by reaction of 6-deoxy-6-iodo- or 6 -deoxy-6 -iodo-sucrose hepta-acetate, respec- 

An Improved method of converting 1,2-diols into alkenes via the thionocarbonates involves use of 1,3-dimethyl-2-phenyl-l,3,2-diazaphospholldine (prepared from N,N-dlmethylethylenedlamine and dlchlorophenylphosphine). An example in the alditol series and one with a pyranold compound were given yields were in the region of 

2-unsaturated 2,6-anhydroheptitol derivative (1 ) which is related to 6-deoxyhex-5-enopyranoses has been prepared from the iodotosylate (15) by standard methods,and the related, furanoid compounds (l6) (Z and E isomers) are present amongst the products of thermolysis of a-D-fructofuranose penta-acetate in acetone solution at 265°C. Furanoid peracetates, however, generally lose 

Hetero Diels-Alder reaction of the oxygenated dienes (17)-(20) with diethyl mesoxalate gave a set of 5,6-dlhydro-(2H) pyrans containing the structural unit (21) which are related to 2,3- 

Michael additions to the nitro-compound (24) have been further examined. Differences were noted with change in the reagent, and the results were discussed in conformational terms and in comparison with those obtained with a related 2-nitroglycal derivative. Photolysis of the enediol ester (25), which was formed on treatment of methyl 3-0-benzoyl-4,6- -benzylidene-a-D-glucopyranoslde with DMSO-acetlc anhydride, gave the unexpected 

An ingenious route to the enone (28) involves ring expansion of 

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Reactivity and yields are greatly enhanced by the presence of 0.5-1% Na in the Li. The reaction is also generally available for the preparation of metal alkyls of the heavier Group 1 metals. Lithium aryls are best prepared by metal-halogen exchange using LiBu" and an aryl iodide, and transmetalation is the most convenient route to vinyl, allyl and other unsaturated derivatives ... 

The fact that crosslinking proceeds at considerably high conversions of the monomers (50%) and at copolymerization temperatures > 60 °C is a distinctive feature of this system, as compared with systems containing other unsaturated derivatives of acrylic acids, which is determined by the difunctional nature of 10. 

The oxidative cleavage of unsaturated ketones takes place under the same conditions as that of alkenes or other unsaturated derivatives. The fate of the primary fission product depends on the position of the double bond with respect to the carbonyl group and on the subsequent reactions. Ozonization of A -cholestenone in acetic acid and ethyl acetate, followed by treatment with 30% hydrogen peroxide, gives a keto acid, evidently resulting from the decomposition of the primarily formed diketo acid (equation 444) [1176]. 

Hikasa et al. (76) interpreted the results of these studies as indicating that cholesterol stone formation in hamsters is related to a relative deficiency in the supply of linoleic acid or its conversion to arachidonic acid and other unsaturated derivatives by pathways dependent on pyridoxal phosphate. Nonabsorbable carbohydrates were thought to favor growth of elements of the bacterial flora that produce vitamin Be and thus prevent stone formation. Diets high in saturated and short-chain fats, and low in linoleic acid, may also inhibit conversion of pyrisoxine to pyrisoxal phosphate and so favor stone... 

Phenyl gtyco l sulphones can be converted into l-(phenyIsulphonyl)glycals and hence 2,3-unsaturated aldonolactones (see under "Other Unsaturated Derivatives"). The reaction of the 2-(p-totylsulphonyl)glycal (11) with sodium methoxide gives the product (12) of 8 2 displacement together with the methanol adduct (13) (Scheme 5). The use... 

Alkenyl and other unsaturated derivatives. A C n.m.r. study of Bu C= C- Li in THF revealed 1 dimeric and 3 different tetrameric aggregates the tetramers probably only differ in number of THF molecules of solvation. ... 

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