Pyranosiduloses. II. The synthesis and properties of some alkyl 2,3-dideoxy-2-enopyranosid-4-uloses

Can. J. Chem. 58, 2694 (1980. The photo-induced alkylation of enone 6 with ethylene glycol gave an adduct from which the a-D-threo (16) and a-D-erythro (17) modifications of structure 2 have been elaborated. It was thereby shown that 2 is not the structure of pillarose. Addition of vinyl magnesium bromide to the ketone 24b gave a slight excess of one allylic alcohol, 25, which upon treatment with osmium tetroxide and hydrogen peroxide gave directly the a,a'-ketodiol3a. The epimer of the latter 33b was available via carboxymethylenation of ketone 24b, reduction of ester, and hydroxylation. Benzoylation of these epimers gave 3b and 33c respectively and it was concluded that the former, methyl 2,3,6-trideoxy-4-C-[oxo(benzoyloxymethyl)methyl]-a-~-threo-hexopyranoside, 3b, is the enantiomer of the "methyl 8-0-benzoyl pillaroside" obtained from the antibiotic pillaromycin A.BERT FRASER-REID et DAVID LOUIS WALKER. Can. J. Chem. 58,2694Chem. 58, (1980. L'alkylation photo induite de 1'Cnone 6 par I'ethylkneglycol donne un adduit a partir duquel on a 6tudiC soigneusement les composes a-D-thrio (16) et a-D-e'rythro (17) qui resultent des modifications de la structure du compose 2. On a ainsi montrk que le compos6 2 ne repr6sente pas la structure de la pillarose. L'addition du bromure de vinylmagnesium sur la cCtone 246, donne un Mger excks de l'alcool allylique 25 qui, traite par le t6traoxyde d'osmium et l'eau oxygCnCe, conduit directement au cktodiol-a,af 3a. L'Cpimbre de ce dernier 33b est prepare par la carboxymCthyl6nation de la c6tone 24b et la reduction de I'ester suivie d'une hydroxylation. Par benzoylation, les Cpimkres conduisent respectivement a 3b et 33c et on aconclu que le premier des deux soit le m6thyltrideoxy-2,3,6 C-(oxo(benzoyloxym6thyl)-methyl)-4 a-D-thre'o hexopyrannoside 3b est I'6nantiomkre du "methyl-0-benzoyl-8 pillaroside" obtenu partir de l'antibiotique pillaromycine A.[ Traduit par le journal]Introduction the aglycones of l a (2b) and those of daunomycin Current interest in the anthracycline antibiotics and its analogues. For example in lb, ( a ) the acetyl runs very high (1) because of the antitumor activity side chain is at C8 rather than C9, (b) the site of displayed by many members of this family. Pillaro-unsaturation in ring A is unusual, (c) the sugar is mycin A, l a , isolated from cultures of Streptomyces attached at the ring junction rather than at C7, and Javovirens, was no exception since it displayed (d) the sugar is linked through a tertiary rather than colchicine-like antitumor activity, and relatively low secondary Oxygen. toxicity (2a). From the standpoint of structure, conThe structure originally assigned to the sugar siderable interest centres around the differences in moiety, ~illarose, was equally unique in being a tricarbonyl sugar with a two-carbon branch located at C2 (2c). We therefore set out to confirm this assign-

Section: Synthesis Of Methyl 8-0-benzoyl-a-d-pillarose 3bsupporting

confidence: 78%

Section: Synthesis Of Methyl 8-0-benzoyl-a-d-pillarose 3bmentioning

confidence: 99%

Pillaromycin-A: structural and synthetic studies related to the sugar moiety, pillarose

Fraser‐Reid¹,

Walker²

1980

“…Both compounds characterized as their dinitrobenzoate esters l b and 2b respectively gave satisfactory microanalyses (3). As expected for an anomeric pair, both l a and 2a lost the aglycon readily (4) to give the same strong ion, 3, corresponding to M+-OCH,CH, at nz/e 99.…”

mentioning

confidence: 62%

An Apparent Stereochemical Effect in MnO₂ Oxidation of Some Allylic Alcohols

Fraser‐Reid¹,

Carthy²,

Holder³

et al. 1971

Self Cite

3,4-Di-0-acetyl-D-xylal undergoes acid-catalyzed reaction with ethanol to give the anomeric mixture of ethyl 2,3-dideoxy-4-0-acetyl-~-glycero-pent-2-enopyranosides which can be separated after deacetylation.The a-D anomer 1 is readily oxidized by manganese dioxide to the a,p-unsaturated ketone but the p-D anomer 2 is inert. Thorough investigation of the 100 and 220 MHz n.m.r. spectra of 1 and 2, their acetates, and dinitrobenzoates indicates that each exists conformationally pure in the half-chair form having the benefit of the anomeric effect. Hence in the oxidizable anomer 1 the C-4 allylic hydroxyl group is pseudoequatorial; in the unoxidizable one it is pseudoaxial. Hydrogen bonding does not appear to be the reason for failure of 2 to oxidize.The ethoxy groups of 1 and 2 are found to be ABX, system with unusually large separation for the AB protons.Le di-O-acktyl-3,4-~-xylal soumis B une reaction acido-catalysee dans l'ethanol, donne un melange anomtrique de dideoxy-2,3-0-acetyl-4-D glyckro-pentene-2-pyranosides d'kthyle. L'isomere-a-D-1 est rapidement oxyde par le bioxyde de manganese en cetone or,p insaturee, par contre l'isornere P 2 est inerte. L'examen des composCs 1 et 2 iinsi que de leurs derives acetates et dinitrobenzoates, en r.m.n. 100 et 220 MHz a montrC que chacun des isomtres est exclusivement sous forme d'une dernie chaise gr%ce ii "l'effet anomkrique". Ainsi, I'isomere oxydC 1 possede line hydroxyle allylique en C-4 pseudo equatorial. Tandis que dans 2, le rn&me groupe est pseudo axial.Les groupes ethoxy dans 1 et 2 forrnent des systemes ABX, avec une separation inhabituellement grande des protons AB.Canadian Journal of Chemistry, 49,3038 (1971) In a recent publication from this laboratory (1) it was reported that when ethanol reacted with 3,4-di-0-acetyl-D-xylal under boron trifluoride catalysis (2) a mixture was produced which, after deacetylation, could be separated chromatographically into what appeared to be a-and P-anomers of ethyl 2,3-dideoxy-Dglycero-pent-2-enopyranoside. The faster running component l a behaved normally on manganese dioxide oxidation, being converted to an a,P-unsaturated ketone within 8 h. The slower running substance 2a, however, gave no evidence for ketone formation after 14 days of exposure to manganese dioxide.It seemed strange that l a and 2a would display such a difference in oxidizability if the only difference between both compounds was 'Undergraduate research participant, summer 1970. Department of Chemistry, University of Waterloo, Waterloo, Ontario. 2Revision received June 10, 1971. the orientation of the ethoxy group at the remote anomeric center. Both compounds characterized as their dinitrobenzoate esters l b and 2b respectively gave satisfactory microanalyses (3). As expected for an anomeric pair, both l a and 2a lost the aglycon readily (4) to give the same strong ion, 3, corresponding to M+-OCH,CH, at nz/e 99. Structure 4 which could also lead to ion 3 is excluded since 1 and 2 from their n.m.r. and i.r. spectra are not vinyl ethers. The speci...

“…When the crude pyrolysate was chromatographed on a silica column using benzene as eluant a compound whose n.m.r. spectrum was identical to the known diene 13 (16) . .…”

Section: 6-o-benzylidene-l23-trideoxy-3-c-1nethylene-~-mentioning

confidence: 59%

“…Thus the crude pyrolysate was treated with methanol and p-toluenesulfonic acid and after neutralization and concentration the residue was partitioned between ether and water. The aqueous phase yielded 6a which was then oxidized using active manganese dioxide in chloroform (16) to give the desired ketone 7.…”

mentioning

confidence: 99%

The 2- and 3-C-Methyl Derivatives of Methyl 2,3-Dideoxy-α-D-erythro-hex-2-enopyranosid-4-ulose

Hicks¹,

Fraser‐Reid²

1975

The oxirane rings of carbohydrate 2,3-anhydro sugars are opened stereospecifically by lithium dimethyl cuprate. These reactions go in high yields, without the formation of abberant side products encountered with other organometallic reagents. The alcohols produced are converted via their xanthate esters to olefins in good overall yields. The latter on hydrolysis and oxidation give the title enones.