A process for producing D-allosan (IV) from levoglucosenone (I) in a high yield, which comprises reducing the 2-carbonyl group of levoglucosenone, inverting the configuration of the resultant hydroxyl group from α to β, protecting it by acylation to give a compound (III), conducting α-cis addition of two hydroxyl groups to the double bond of the compound (III), and removing the protective group.
The stereoselective reduction and cis-dihydroxylation of levoglucosenone (1,6-anhydro-3,4-dideoxy-beta-D-glycero-hex-3-enopyranos-2-ulose), gave D-allosan (1,6-anhydro-beta-D-allopyranose) in high yield.
Synthesis of Methylene-Expanded 2‘,3‘-Dideoxyribonucleosides
作者:Michael E. Jung、Mehrak Kiankarimi
DOI:10.1021/jo980436l
日期:1998.11.1
A method for the preparation of methylene-expanded 2',3'-dideoxyribonucleosides is reported. The very inexpensive starting material levoglucosenone 8 was converted into the known mixture of alcohols 12ab which were converted into the required silyl ether alcohol 26 in six steps via either of two routes. The first involved a one-step acetylation and opening of the anhydro sugar bridge to give the triacetates 20ab which were reduced with triethylsilane and silyl triflate to afford the diacetates 21ab, both of which gave 26 after further functional group conversions. The second route entailed a simple acetylation of 12ab followed by reduction with triethylsilane and silyl triflate to give the monoacetates 19ab, both converted via straightforward chemistry into 26. Mesylation of the alcohol of 26 furnished the mesylate 27. Alkylation of adenine with the mesylate 27 afforded the silyl ether 28 which was deprotected to give the desired modified dideoxy nucleoside 7a. Alkylation of 2,6-diaminopurine 38 with the mesylate gave the protected diaminopurine nucleoside 39. Upon acetylation, it produced a mixture of di- and monoacetates 40-41, the latter of which was transformed into the desired guanosine analogue 7e. Thus, two new nucleoside analogues 7ae were prepared from levoglucosenone 8.
US5457192A
申请人:——
公开号:US5457192A
公开(公告)日:1995-10-10
Method of manufacturing D-allosan
申请人:Japan Tobacco Inc.
公开号:US05457192A1
公开(公告)日:1995-10-10
The carbonyl group at the 2-position of levoglucosenone is reduced to obtain a hydroxyl group having a .beta.-configuration. The hydroxyl group having a .beta.-configuration is reversed to an .alpha.-configuration, and hydroxyl groups are added at the 3- and 4-positions in a cis-.alpha. form. Finally, the protective group of the hydroxyl group at the 2-position is eliminated. The reduction of the carbonyl group at the 2-position can be performed such that the levoglucosenone is reacted with aluminum lithium hydride or sodium boron hydride in an appropriate solvent. Reversion of the hydroxyl group having a .beta.-configuration can be performed by the Mitsunobu method or a method having a mesylation step and a step using cesium acetate. The addition of the hydroxyl groups to the 3-and 4-positions in the cis form can be performed by oxidizing the double bond across the 3- and 4-positions with an appropriate oxidizing agent. The elimination of the protective group of the hydroxyl group at the 2-position can be performed under basic conditions in accordance with normal methods. According to the method of the present invention, D-allosan can be obtained stereoselectively in high yield via a smaller number of steps than that of the conventional synthesis method.