Study On Synthesis Of Cyclic Dinucleotide Based On Targeting Stimulator Of Interferon Gene

Cyclic dinucleotide is secondary messenger of microorganisms with the function to regulate the pathogenicity and morphology of the pathogenic microbes.Cyclic dinucleotide can not only be recognized by human immune system to curb the attack from the pathogens,but also can stimulate the secretion of cytokines to kill cancer cells.This paper provides a new way to obtain cyclic dinucleotides,the process has several advantages including mild reaction conditions,simple operation and low cost.The work of this paper mainly includes the following three parts:In the first part,the synthesis began with the guanosine,amino and hydroxyl groups of with were temporary protected by trimethyl silyl groups,the protected intermediate reacted with isobutyryl chloride,followed by all of trimethyl silyl groups were removed,to get N2-isobutyryl guanosine.The 5'-OH and3'-OH of N2-isobutyryl guanosine were selectivity protected with DMTrC1 and TBDMSCl;After phosphorylation,we get N2-isobutyryl-5'-O-(4,4'-dimethoxytrityl)-3'-O-tert-butyldimethylsilyl-2'-O-[(2-cyanoethyl)-N,N-diisopropylaminophosphinyl] guanosine 2-12.The preparation of 2-7 started with adenosine,reacted with acetic anhydride to protect the 2',3',5'-OH of which;After acetylation with benzoyl chloride of amino on the temporary protected adenine and removal the 2',3',5'-OH protected groups,we get N6-benzoyladenosine.DMTrC1 protected the 5'-OH,TBDMSCl protected the 2'-OH,Levulinic acide protected the 3'-OH,and then 5'-deprotection,we perpared the important intermediate N6-benzoyl-2?-O-tert-butyldimethylsilyl-3?-O-levulinyl adenosine 2-7.2-13 was synthesized from the reaction of intermediate 2-12 with 2-7 and isolated in a yield of 90% after P(III)oxidation.3'-/5'-deprotection,and purification.Using 1H-tetrazole and 2-cyanoethyl tetraisopropylphos phordiamidite and was followed by an in situ intramolecular cyclization,which was isolated in a yield of 81% after P(III)oxidation and purification,deprotection give the compound 2',3'-cGAMP.In the second part,the N2-isobutyryl-5'-O-(4,4'-dimethoxytrityl)-2'-O-tert-butyldimethylsilyl-3'-O-[(2-cyanoethyl)-N,N-diisopropylaminophosphinyl] guanosine 3-1 were synthesized by phosphorylation reaction from the intermediate 2-10.The intermediate 3-1 was coupled with the 2-7 in the presence of acetonitrile and 1H-tetrazole and the yield after oxidation was 95%.Followed by 3'-/5'-deprotection to givethe linear dimmers,then in situ intramolecular cyclization and the yield after oxidation was 86%.Finally the target compound 3',3'-cGAMP was obtained by deprotection.In the third part,after phosphorylation,we get the compound N6-benzoyladenoside-5'-O-(4,4'-dimethoxytrityl)-2'-O-tert-butyldimethylsilyl-3'-O-[(2-cyanoethyl)-N,N-diisopropylaminophosphinyl]adenosine 4-1.The intermediates 4-1 and 2-7 were coupled under the presence of acetonitrile and1H-tetrazole.And then in situ intramolecular cyclization,4-4 was isolated in a yield of 83% after P(III)oxidation and purification,removal of the protecting group to give 3',3'-c-di-AMP.