Ketoses, synthesis 1-deoxy

Com. Esp. Deterg., 11th, 1980, S. 255-266 . .Synthesis of Detergents. l-n-Alkylamino-l-deOxy-2-ketoses, 2-n-Alkylamino-2-deoxy-D-glusoses, and Derivatives11. 

In DERA reactions, where acetaldehyde is the donor, products are also themselves aldehydes. In certain cases a second aldol reaction will proceed until a product has been formed that can cyclize to a stable hemiacetal.71 For example, when a-substituted aldehydes were used, containing functionality that could not cyclize to a hemiacetal after the first aldol reaction, these products reacted with a second molecule of acetaldehyde to form 2,4-dideoxyhexoses, which then cyclized to a hemiacetal, preventing further reaction. Oxidation of these materials to the corresponding lactone, provided a rapid entry to the mevinic acids and compactins (Scheme 5.43). Similar sequential aldol reactions have been studied, where two enzyme systems have been employed72 (Scheme 5.44). The synthesis of 5-deoxy ketoses with three substitutents in the axial position was accomplished by the application of DERA and RAMA in one-pot (Scheme 5.44). The long reaction time required for the formation of these thermodynamically less stable products, results in some breakdown of the normally observed stereoselectivity of the DERA and FDP aldolases. In a two-pot procedure, DERA and NeuAc aldolase have... 

C. Aug6, C. Gautheron, S. David, A. Malleron, B. Cavayd, and B. Bouxom, Sialyl aldolase in organic synthesis From the trout egg acid, 3-deoxy-D-g7ycero-D-ga/acto-2-nonulosonic acid (KDN), to branched-chain higher ketoses as possible new chitons, Tetrahedron 46 201 (1990)... 

Extension and elaboration of the original nitromethane work continued to occupy the attention of Sowden and his collaborators until his death. A convenient synthesis of 2-deoxy-D-er2/f/tro-pentose was a particularly noteworthy achievement, and the substitution of 2-nitroethanol for nitromethane opened the door to the ketoses. The addition of sodium meth-oxide or ammonia to C-nitro-olefins also provided convenient means for preparing 2-0-methyl derivatives and 2-amino sugars, respectively. 

Osmylation of the chirally masked 2-alkoxypent-3-enal 1 and subsequent functional group manipulations furnished enantiopure 5-deoxy-L-lyxose and -xylose derivatives. A new preparation of 5-deoxyribonolactone derivative 2 from ribonolactone by tributyltin hydride reduction of a 5-chloro-5-deoxy intermediate has been published. Conversion of compound 2 to a 5 -deoxy-nucleoside analogue is covered in Chapter 20. A multistep synthesis of methyl 5-0-benzoyl-2,3-dideoxy-P-D-g/ycero-pentofuranose (4) from D-xylose involving Raney nickel desulfurization of compound 3 (see Chapter 11) has been described. Several deoxy-ketoses have been prepared by Raney nickel desulfurization of 1-thio-ketose derivatives obtained by enzyme-catalysed aldol condensations (see Vol. 29, Chapter 2, Scheme 1). An example is given in Scheme 1. ... 

Cheap methods for the synthesis of various deoxy alditols and ketoses with three to six carbon atoms have been developed, with acetylene as the starting material la). Propargyl alcohol (l-propyn-3-ol) and 3-butyn-2-ol are important intermediates. Formaldehyde or acetaldehyde react with hydrogen atoms adjacent to a triple bond, in the presence of copper acety-lide catalyst. 

The synthesis of ketose nucleosides from 1-deoxy-l-nitro-D-ribose is covered in Chapter 20. 

The preparation of glycopeptides by glycosylation of peptides with glycals using N-iodosuccinimide is covered in Chapter 3, and the preparation of chlorodeoxy-l,4 3,6-dianhydroalditols is mentioned in Chapter 18. The synthesis of 1-chloro-1-deoxy-ketoses by a 1 carbon homologation of lactone derivatives is outlined in Chapter 12. 

A route to ketose-derived nucleosides relies upon the 1-deoxy-l-nitro-ribofuranose derivative (18) as an important intermediate. Henry reaction of this was the key to the synthesis of psicouridine (20) outlined in Scheme 3, anomer (19) being the major kinetic product initially formed. Alternatively, Michael reactions of (18) with, for example, acrylonitrile, permitted the introduction of 3-carbon chains at the anomeric position. l... 

This decarboxylation reaction serves as the tool for enzyme-mediated organic synthesis [136,137]. As seen in Eq. (27), the addition of thiazolium intermediate derived from hy-droxypyruvate proceeds via re face attack to afford the products (76) with stereochemically defined 2,3-erythro stereochemistry. The examples are summarized in Table 7. This method works very well for the synthesis of naturally occurring phosphorylated [126,134], nonphosphorylated ketoses [120,125], and deoxy sugars [115,124]. Moreover, 2,3-erythro-dio motif is exemplified in the chemoenzymatic synthesis of die L-series of aldoses (77-79) [122], aza sugars (80,81) [128-130] and ( )-gjco-brevicomin (69), an insect pheromone [131] (Tab e 8). The stereochemically controlled syntiiesis of aldehydes with d(2) config-... 

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