Synthesis of D -chalcose

The syntheses of three a-cyclopropylcarbonyl compounds of carbohydrate origin, 1, 2, 3, are described. The cyclopropyl carboxaldehyde 1 was obtained from the corresponding carbinol by manganese dioxide oxidation of the primary alcohol. However, the secondary cyclopropyl alcohol in 8 did not respond to manganese dioxide and its oxidation (in the tritylated derivative (14), to the cyclopropyl ketone, 2, had to be achieved by ruthenium tetroxide. The sequence leading to 2 (via 8) began with ethyl 4,6-di-0-acetyl-2,3-dideoxy-a-D-erythro-hex-2-enopyranoside 11, which added methylene to give the a-D-a110 configuration with the cyclopropane ring syn to the glycosidic ethoxy group. The diastereomeric tritylated cyclopropyl ketone 3, possessing the cyclopropyl ring anti to the ethoxy group, resulted from cyclopropanation of the a/3-unsaturated ketone, 15. In the latter case, the acetoxy group apparently provides greater directing influence to the incoming methylene than does the allylic ethoxy group.Les syntheses de trois composts a-cyclopropylcarbonyles d'origine carbohydrate, 1, 2, 3 sont dtcrites. Le cyclopropyl carboxaldthyde 1 a t t t obtenu a partir du carbinol correspondant, par oxydation au dioxyde de manganese de I'alcool primaire. Cependant, le cyclopropylalcool secondaire dans 8 ne rtagit pas sur le dioxyde de manganese et son oxydation (dans le dtrivt tritylt 14) en cyclopropylcttone 2 a dti &tre effectute par le tttroxyde de ruthtnium. La stquence conduisant a 2 (via 8) commence avec I'tthyl di-0-acttyl-4,6 did6oxy-2,3-a-~-i.rythro hexeno-2 pyranoside 11, qui par addition de methylbne conduit a la configuration a-D-all0 avec le cycle cyclopropane en syn par rapport au groupe tthoxy glycosidique. La cyclopropylcttone tritylee diasttreoisomere 3, avec le cyclopropyl en anti par rapport au groupe tthoxy, rtsulte de la cyclopropanation de la cttone a/3 insaturee 15. Dans ce dernier cas, le groupe acttoxy oriente apparemment de faqon plus grande le methylene qui entre, que ne le fait le groupe tthoxy allylique.

Section: Methyl 46-0-benzylidene-23-dideoxy-23-c-(exo-mentioning

confidence: 99%

The Synthesis of some α-Cyclopropylcarbonyl Glycopyranosides

Fraser‐Reid¹,

Carthy²

1972

“…Results and Discussion In an earlier publication (1) it was reported that methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside was converted into methyl 4,6-dideoxy-a-D-xjlo-hexopyranoside by hydrogenation over Raney nickel in the presence of potassium hydroxide; however, when triethylamine was substituted for potassium hydroxide, a selective, reductive dechlorination occurred a t C-4 to give methyl 6-chioro-4,6-dideoxy-a-Dxylo-hexopyranoside. The observed selectivity is potentially of considerable significance in synthesis.…”

Section: Introductionmentioning

confidence: 92%

Selective, reductive dechlorination of chlorodeoxy sugars. Structural determination of chlorodeoxy and deoxy sugars by ¹³C nuclear magnetic resonance spectroscopy

Szarek¹,

Zamojski²,

Gibson³

et al. 1976

Self Cite

The reductive dechlorination of chlorodeoxy sugars by hydrogenation over Raney nickel in the presence of potassium hydroxide or triethylamine has been investigated; a selective dechlorination was observed in most cases with triethylamine. Several new, chlorodeoxy furanoid derivatives have been synthesized by the use of triphenylphosphine–carbon tetrachloride. 13C magnetic resonance spectroscopy has been employed for the assignment of structure to the chlorodeoxy sugars and the corresponding reduced products.

“…(9). The crystalline product was recrystallized from ether-petroleum ether to give white needles (0.8 g, 84%), whose physical constants were the same as those reported previously (8) Metl1yl4,6-O-Benzylicler1e-2,3-dideoxy-3-C-nlethyler~e-a-L-erylhro-hexopyrnr~oside (3) To a solution of methylenetriphenylphosphorane [prepared, as described by Lance and Szarek (15), from rnethyltriphenylphosphonium bromide (1.4 g) and sodium amide (0.21 g)] in ether (10 nil) was added dropwise, with stirring and at reflux temperature, a solution of ketone 2 (0.7 g) in ether (10 ml).…”

Section: Metftyl46-o-benzylidetie-2-deoxy-a-~-rryti1ro-fie~0-mentioning

confidence: 99%

Synthesis of olivomycose (2,6-dideoxy-3-C-methyl-L-arabino-hexose)

Williams¹,

Szarek²,

Jones³

1969

Self Cite

Oxidation of niethyl 4,6-0-benzylidene-2-deoxy-a-~-~rnbit1o-1iexopyranoside (I) with ruthenium tetroxide gavc the 3-ketone 2 in high yield. A Wittig reaction between niethylenetriphenylphosphorane and compound 2gave niethyl 4,6-O-benzyIidene-2.3-dideoxy-3-C-niethylene-a-~-ery~/zro-hexopyranoside (3), which was hydrated by the oxynierci~ration-de~nercilration procedure to afford methyl 4,6-0-benzylidcnc-2-deoxy-3-C-riiethyl-a-~-~rabito-lexopyranoside (4). The reaction of compound 4 with N-bromosuccinimide gave methyl 4-O-bcnzoyl-6-bromo-2,6-dideoxy-3-C-methyl--~-nrbito-hexopyranoside (5) in high yield. Treatment of compound 5 with lithii~ni aluniini~~ni hydride followed by acid-catalyzed hydrolysis of the resultant product, gavc L-olivomycose (6).L'oxydation par le titroxyde de ruthCnium du ni8thyl 4,6-0-benzylidene-2-dCsoxy-r-~-m.abit1o-l~txopyranosidc (1) conduit avec un trks bon rendernent a la cetone 2. Une reaction de Wittig entre le compose 2 et le mCthylenetriphCnylphosphorane donne le niCthyl 4,6-0-benzylidene-2,3-didesoxy-3-CmCtliyli.ne-a-~-i~'j~tI~r~~-hCxopyranoside (3), qiri par hydratation par la rbaction d'oxyniercurationdtmercilration donne le methyl 4 , 6 -0 -b e n z y l i d e n e -2 -d C s o x y -3 -C -n i~t h y l -~x o p y r a n o s i d e