- Nucleic acid related compounds. 81. Syntheses of 9-(3-deoxy-β-D-threo- pentofuranosyl)adenine, the core nucleoside of the extraordinarily selective antibiotic agrocin 84, and simplified structural component analogues
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Alternative syntheses of 9-(3-deoxy-β-D-threo-pentofuranosyl)adenine (4), the core nucleoside of agrocin 84 [and its 2'-deoxy threo isomer 5] were devised: (1) direct conversion of 9-(β-D-arabinofuranosyl)adenine into 9- (2,3-anhydro-β-D-lyxofuranosyl)adenine and regioselective opening of its oxirane ring with sodium borohydride to give 4 and 5 (~7.5:1); (2) treatment of adenosine with sodium hydride and 2,4,6-triisopropylbenzenesulfonyl chloride, and subjection of the resulting 2'(3')-sulfonates to the reductive [1,2]-hydride shift rearrangement with lithium triethylborohydride to give 4 and 5 (~2:1); and (3) subjection of the phenoxythiocarbonyl esters of 9- [2(3),5-bis-O-(tert-butyldimethylsilyl)-β-D-arabinofuranosyl]adenine to Barton deoxygenation, and deprotection to give 4 and 2'-deoxyadenosine (~5:1). Methods (2) and (3) gave lower yields. Syntheses of simplified 6-N- and 5'-O-adenosine phosphoramidate model compounds were explored to examine potential access to such features in the structure proposed for agrocin 84.
- Vinayak,Hansske,Robins
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p. 1181 - 1189
(2007/10/02)
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- REACTION OF ADENINE NUCLEOSIDES, TOSYLATED IN THE CARBOHYDRATE MOIETY, WITH LITHIUM TRIETHYLBOROHYDRIDE
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The reaction of lithium triethylborohydride with the 2',3'-di-O-p-tolylsulphonyl derivatives of 9-β-D-ribofuranosyladenine, 9-β-D-arabinofuranosyladenine, 9-β-D-xylofuranosyladenine and 9-β-D-lyxofuranosyladenine was studied.The reaction of 2',3'-di-O-p-tolylsulphonyladenosine with LiEt3BH gave 9-(3-deoxy-β-D-threo-pentofuranosyl)adenine.This rearrangement reaction was used for the synthesis of 9-(3,5-dideoxy-β-D-threo-pentofuranosyl)adenine in one step from 2',3',5'-tri-O-p-tolylsulphonyladenosine in 58percent yield.The p-tolylsulphonyl group in the 2'-"up" configuration of unprotected adenine nucleosides was preferentially attacked by LiEt3BH giving S-O-bond scission.This was shown by the formation of 9-(3-deoxy-β-D-threo-pentofuranosyl)adenine from 2',3'-di-O-p-tolylsulphonyl-9-β-D-arabinofuranosyladenine and by the formation of 9-β-D-lyxofuranosyladenine from 2'-O-p-tolylsulphonyl-9-β-D-lyxofuranosyladenine with LiEt3BH. 9-β-D-Lyxofuranosyladenine was synthesized from 3',5'-di-O-benzoyl-9-β-D-xylofuranosyladenosine in 88percent yield using a triflate displacement reaction.
- Herdewijn, Piet
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p. 6563 - 6580
(2007/10/02)
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