The first total synthesis of lamellarin alpha 20-sulfate (1), a selective inhibitor of HIV-1 integrase, has been completed. The lamellarin alpha core in which 13-OH and 20-OH were differentially protected by isopropyl and benzyl groups, respectively, was constructed by using Hinsberg-type pyrrole synthesis and Suzuki-Miyaura coupling as the key reactions. The 20-sulfate was prepared by a sequence including debenzylation of 20-OBn, 2,2,2-trichloroethylsulfation of the resulting 20-OH deprotection of 13-Oi-Pr, and final reductive cleavage of the 2,2,2-trichloroethyl ester. (c) 2006 Elsevier Ltd. All rights reserved.
Synthesis, structure–activity relationships, and mechanism of action of anti-HIV-1 lamellarin α 20-sulfate analogues
Lamellarin a and six different types of lamellarin alpha 20-sulfate analogues were synthesized and their structure-activity relationships were investigated using a single round HIV-1 vector infection assay. All lamellarin sulfates having pentacyclic lamellarin core exhibited anti-HIV-1 activity at a 10 mu M concentration range regardless of the number and position of the sulfate group. On the other hand, non-sulfated lamellarin alpha and ring-opened lamellarin sulfate analogues did not affect HIV-1 vector infection in similar concentrations. The lamellarin sulfates utilized in this study did not exhibit unfavorable cytotoxic effect under the concentrations tested (IC50 > 100 mu M). Confocal laser scanning microscopic analysis indicated that hydrophilic lamellarin sulfates were hardly incorporated in the cell. HIV-1 Env-mediated cell-cell fusion was suppressed by lamellarin sulfates. These results suggested that lamellarin sulfates have a novel anti-HIV-1 activity besides the previously reported integrase activity inhibition, possibly at a viral entry step of HIV-1 replication. (C) 2011 Elsevier Ltd. All rights reserved.
Short and flexible route to 3,4-diarylpyrrole marine alkaloids: syntheses of permethyl storniamide A, ningalin B, and lamellarin G trimethyl ether
4-diarylpyrrole marine alkaloids has been developed using Hinsberg-type pyrrole synthesis and palladium-catalyzed Suzuki cross-coupling of the 3,4-dihydroxypyrrole bis-triflate derivatives as key reactions. Based on this approach, formal syntheses of permethyl storniamide A and ningalin B, and a total synthesis of lamellarinGtrimethylether have been achieved.