Psicose 6-methyl

Some examples will illustrate the applicability of this generalization in so far as it concerns alkaline scission. 5,6-Anhydro-l,2-isopropylidene-D-glucofuranose with alcoholic sodium hydroxide gives a mixture of isopropylidene-D-glucose and isopropylidene-L-idose. The latter results from inversion on C5, the former presumably by inversion on the non-asymmetric C6.7 3,4-Anhydro-l,2-isopropylidene-D-psicose (or allu-lose17) (XX) when treated with sodium hydroxide yields a mixture of products among which 1,2-isopropylidene-D-fructose (XIX) was detected (in the representations inversions are denoted by circles above the arrows and the carbons inverted are noted below the arrows). With sodium methoxide, however, l,2-isopropylidene-4-methyl-D-sorbose (XXI) is the chief product and results from inversion on C4.1S... 

The composition of a solution of 3-O-methyl-D-psicose15 at 27° is 31 7 56 6, whereas that of D-psicose is 22 24 39 15. In this case, the methoxyl group in the / -pyranose form (17) is axial, and 1,3-parallel interaction with one of its equatorial neighbors cannot be avoided. There is a similar interaction in the / -furanose form, too, but not in the a anomers. 

The composition of 6-0-methyl-D-ii/ to-2-hexulose (6-O-methyl-D-tagatose) in aqueous solution at 35° is 21% of a-furanose, 69% of/ -fura-nose, and 10% of the keto form.15 The ratio of a- to / -furanose for 6-0-methyl-D-psicose was found to be — 2.4 1 that of a- to / pyranose for 5-O-methyl-D-psicose, —1.25 1 the proportion of the keto form was not determined.13... 

Ohle and Just112 have carried out the following sequence 1,2-isopro-pylidene-D-fructopyranose 3-p-toluenesulfonate —> l,2-isopvopylidene-3,4-anhydro-D-psicose —> l,2-isopropylidene-4-methyl-D-sorbose (VII), ([a]D -81.6°). Since the introduction of a methyl group does not alter greatly the specific rotation, it is to be expected that the parent 1,2-iso-... 

In the sorbose series 3-methyl-D-sorbo8e14 has been synthesized, as well as the aforementioned 4-methyl-8 derivative the latter compound was obtained in a series of reactions from D-fructose derivatives through l,2-isopropylidene-3,4-anhydro-D-psicose. In the earlier study8 the configuration of the 4-methyl ketohexose was shown to be that of a D-sorbopyranose by methylation of l,2-isopropylidene-4-methyl-D-sorbose (VI) to the trimethyl derivative (LXV) which was hydrolyzed to 3,4,5-trimethyl-D-sorbose (LXVI). The latter compound, on oxidation, gave derivatives of levorotatory dimethoxysuccinic acid (LXVIII) and xylo-trimethoxyglutaric acid (LXVII). 

Desulfonylation of 2-O-p-tolylsulfonyl or 2-0-(methylsulfonyl) derivatives of D-arabinose, D-xylose, and L-fucose with aqueous barium hydroxide yields D-ribose, D-lyxose, and 6-deoxy-L-talose, respectively, by way of a 1,2-anhydro sugar similarly, 3-0-(methyl-sulfonyl)-D-fructose affords D-psicose. 

Deoxy 6-Deoxy-3-C-methyl-D-psicose C7H14O5 178.185 Syrup. Md -27 (c, 1.46 in H2O). 

Deoxy-3- C -methyl-D-psicose, M-284 l-Deoxy-3-C-methylpsicose, D-311 9-(3-Deoxy-3-C-methylribofnranosyl)adenine, D-312... 

Deoxy-6-iodo-l,2 3,4-di-0-isopropylidene-P-D-psicofuranose, D-269 6-Deoxy-6-iodopsicose D-Furanose-/omi, D-269 l-Deoxy-5,6-0-isopropylidene-D-ri7>o-2-hexulose, D-222 l-Deoxy-2,3-0-isopropylidene-3-C-methyl-a-D-psicofuranose, D-311 l-Deoxy-3-C-methylpsicose D-/omi, D-311 6-Deoxy-3-C-methyl-D-psicose, M-284... 

The value of the 1,3-dithian route to branched-chain sugar derivatives has been illustrated further by stereospecific syntheses of 3-C-formyl, 3-C-hydroxymethyl, and 3-C-methyl derivatives of D-psicose from the ketone (373) via the dithianyl adduct (374). Addition of nitromethane to (373) gave both 3-C-nitromethyl-o-psicose and -fructose derivatives, which, after separation by chromatography, were reduced to the corresponding 3-C-aminomethyl derivatives. The use of dithianyl derivatives in the synthesis of streptomycin components is dealt with in Chapter 18. 

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