Nucleosides 2 -deoxy-4 -thio

This article collates information on the reactivity of sugar isothiocyanates and isomeric thiocyanates, and illustrates some of the chemical properties that have contributed to the synthesis of nucleoside analogs,1719 and thio and deoxy sugars. 

In an article that collates information not extensively treated before, Z. J. Witczak (West Lafayette) describes the synthesis, chemistry, and preparative applications of monosaccharide thiocyanates and isothiocyanates the thiocyanate anion is an ambident nucleophile of great synthetic versatility in approaches to nucleoside analogs and to thio and deoxy sugars. 

The synthesis of 132, starting from S-benzyloxy propanal (131), involved the ring opening of an optically active epoxide 133 with a xanthate anion (Scheme 37)J22 Stereoselective synthesis of 133 by Sharpless epoxidation allowed preparation of the 2-deoxy-4-thio-D- and L-ezyr/zro-pentoses, " which were transformed into the corresponding pyrimidine nucleosides with silylated uracil and McaSiOTf. and then deprotected with Bu NF. 

S-ethyl-3-thio-D-xt/Zo isomer, and Raney nickel desulfurization of 6-amino-9- (2-first synthesis of a naturally occurring purine 2-deoxy-nucleoside to be reported. A number of nucleoside analogs were prepared by modification of the purine moiety before desulfurization. ... 

The yeast nucleoside containing a thio sugar has been shown to be 6-amino-9-(5-d-methyl-5-thio-D-ribofuranosyl)-9i/-purine []5-deoxy-5-(methyIthio)adenosine] (130). 

Dideoxynucleosides can also be prepared by hydrogenolysis of 2, 3 -dideoxy-2 -thio [158], 2, 3 -dideoxy-3 -thio [159, 160], 8,3 -S-anhydronucleo-sides of purine [161] and 2, 3 -dideoxy-3 -halogenoderivatives of nucleosides [52,162,163]. The intermediate dideoxy-3 -thio and 3 -halogeno derivatives can be easily prepared by nucleophilic displacement of the sulfonyloxy group of 2 -deoxy-3 -0-mesyl or tosyl nucleosides with mercaptide anion or with halide ion, respectively. The procedure has been successfully used for the synthesis of 3 -deoxythymidine 109h, 2, 3 -dideoxyuridine 109i and 2, 3 -dideoxy-5-... 

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. ... 

Structures of a range of base and/or sugar-modified nucleoside analogues have been described. The 6-azacytosine 71, pyrazolo[3,4-/>]quinoline P-ribo-furanoside 72 5 -0-benzoyl-3 -deoxy-2 -keto-a-uridine, 3 -deoxy-3 -5-(2-nitrophenyldisulfanyl)thymidine, ° anhydronucleoside 73, 5-adamantyl-2 -deoxy-4 -thio-a-uridine, the bicyclic nucleoside analogue 74, and bicyclic analogues 75 (both epimers) and 76. ... 

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