SYNTHESIS OF ANHYDRODIDEOXYHEXITOLS RELATED TO ANHYDRODEOXYHEXITOLS FROM OXO REACTION OF 3,4-DI-O-ACETYL-D-XYLAL

Abstract

2,3-Di-O-acetyl-l,5-anhydro-4,6-dideoxy-~-nrabi?~o-hexitol (VI) and 2,3-di-0-acetyl-1,s-anhydro-4,6-dideoxy-I--rylo-hexitol (VII) were prepared by reaction of ~ilethyl magnesium bromide with 3,4-di-0-acetyl-~-xylo-pyra1losyl chloride. An independent synthesis of compounds (VI) and (VII) was also achieved from the 6-0-tosyl derivatives of the 0x0 products from 3,4-di-O-acetyl-~-xylal, thus confirming that the configuration of the secondary hydroxyls of glycals is not inverted during the 0x0 reaction.Part I1 of this series ( I ) showed that application of the 0x0 reaction to 3,4-di-0-acetyl-11-xylal, followed by deacetylation, gave 1,s-anhydro-4-deoxjr-D-arabino-hexitol (I) and 1 ,5-anhydro-4-deoxy-L-xylo-hexitol (I I). The I--configuration of C-5 of (I I) was established by correlation with C-4 of 1,4-anhydro-5-deoxy-D-arabino-hexitol; the C-5 configuration of (I) must therefore be D , a s this anhydrodeoxyhexitol, on cleavage of the 0-glycol bond and reduction, formed a trio1 ether which was the mirror image of that derived from (11). The remaining asymmetric centers of (I) and (11), a t C-2 and C-3, were assuined to be unchanged in configuration from the parent polyol.Von Rudloff et al. (2) carried out the hydrogenolysis of methyl-a-D-glu~op~ranoside a t 210" t o give 1,s-anhydro-4-deoxy-hexitol along with other products. Gorin (3) subsequently sho\\red that the hexitol consisted of two 1,s-anhydro-1-deoxy-D-hexitols. On the bases of coillparative rates of lead tetracetate oxidation and con~parison of observed specific rotations with those calculated from application of the principle of opt-ical superposition, these hexitols were postulated to have structures (I) and (111) (1,;S-anhydro-4-deoxy-D-lyxo-hexitol). The compound t o which they assigned the D-nrabino configuration +19"; tris-p-nitrobenzoate, 111.p. 115-119", [a]D +59") is clearly different from our con~pound (I) ([DID -13"; tris-p-nitrobenzoate, 1n.p. 21;3", [elD -50"). We have accordingly carried out a series of reactions correlating the secondary hydroxyl configurations of (I) and (11) with those of ~-x y l a l , thereby confirming our assignments of structures (I) and (11). Bonner (1) has shown that the hemiacetal halogen of pol yacetylglycos>~l halides undergoes a et eta the tical reaction with Grignard reagent \\.hen the latter is present in sufficient-excess, and has, moreover, provided adecl~~ate experirnental proof to sho\\-that decomposition of the Grignard adduct t o the ester group does not involve rupture of asymmetric bonds, and therefore no change of configuration talres place during reaction with the Grignard reagent. lising the Grignard synthesis ure have been successful in preparing the diacetates of the two 6-deoxy analogues of (I) and (11) For personal use only.

Ophiocerins A−D and Ophioceric Acid: Tetrahydropyran Derivatives and an Africane Sesquiterpenoid from the Freshwater Aquatic Fungus Ophioceras venezuelense

“…28 A few synthetic, protected forms of tetrahydro-6-methylpyran-3,4-diols have also been described. 29,30 The free triol analogue of 4 (1,5-anhydro-D-fucitol) and its enantiomer have been reported as synthetic products 31,32 and as a byproduct of the chemical hydrolysis of suitable glycosides under reducing conditions. 33 Although 4 could be named as a derivative of 1,5-anhydro-D-fucitol, and compounds 1-3 could be formally labeled as 1,5-anhydro-4,6-dideoxyhexitols (or as 6-methyltetrahydropyran-3,4diols), we propose the common names ophiocerins A-D for these metabolites.…”

“…The only reported precedent for a compound with the same 6-methyltetrahydropyran-3,4-diol gross structure as 1 − 3 was obtained during chemical studies of kojic acid as a product of catalytic hydrogenation and was characterized only by elemental analysis, derivatization, and IR spectroscopy . A few synthetic, protected forms of tetrahydro-6-methylpyran-3,4-diols have also been described. , The free triol analogue of 4 (1,5-anhydro- d -fucitol) and its enantiomer have been reported as synthetic products , and as a byproduct of the chemical hydrolysis of suitable glycosides under reducing conditions . Although 4 could be named as a derivative of 1,5-anhydro- d -fucitol, and compounds 1 − 3 could be formally labeled as 1,5-anhydro-4,6-dideoxyhexitols (or as 6-methyltetrahydropyran-3,4-diols), we propose the common names ophiocerins A−D for these metabolites.…”

Amino sugars. LV. Absolute configuration of the carboxyethyl (lactyl) side chain of muramic acid[2-amino-3-0-(D-1-carboxyethyl)-2-deoxy-D-glucose]

“…This degradation was performed on the compound obtained by reduction of the carboxyl group to a hydroxymethyl group because of the possibility of formation of internal esters between the carboxy group of the lactyl residue and the two new hydroxymethyl groups created by the periodate oxidation-sodium borohydride reduction. The p-nitrobenzoyl esters of similar tri(hydroxymethyl) derivatives have been used for the determination of absolute configurations in the carbohydrate field (see Gorin, 1960; Rosenthal andAbson, 1964, 1965). Muramic acid having a reduced side chain 3 was prepared according to the method previously described (Jeanloz and Walker, 1967), except that the reduction of the side chain with lithium borohydride was performed at the stage of the benzylidene derivative of the methyl ester methyl -D-glycoside 1 (see Scheme I) (Flowers .…”