A synthetic route to 9-(polyhydroxyalkyl)purines

Structures and absolute configurations of penicillactones A-C from an endophytic microorganism, Penicillium dangeardii Pitt

Penicillactones A-C (1-3) are structurally related natural products with a spirocyclic anhydride structure and were isolated from the endophytic fungus Penicillium dangeardii Pitt. Penicillactones B and C showed inhibition of the release of β-glucuronidase from polymorphonuclear leukocytes with ED50 values of 2.58 and 1.57 μM. A 2D INADEQUATE experiment of 1 was performed at natural abundance to confirm the arrangement of its carbon skeleton. The configurations of 1-3 were established through extensive NMR spectroscopic analysis, selective structural modifications, and CD analysis.

Third-generation immucillins: syntheses and bioactivities of acyclic immucillin inhibitors of human purine nucleoside phosphorylase

ImmH (1) and DADMe-ImmH (2) are potent inhibitors of human purine nucleoside phoshorylase (PNP), developed by us and currently in clinical trials for the treatment of a variety of T-cell related diseases. Compounds 1 and 2 were used as templates for the design and synthesis of a series of acyclic immucillin analogues (8-38) in order to identify simplified alternatives to 1 and 2. SerMe-ImmG (8) and DATMe-ImmG (9) displayed the lowest inhibition constants of 2.1 and 3.4 pM, respectively, vs PNP. It was postulated that the flexible natures of 8 and 9 enabled them to adopt conformations resembling those of 1 and 2 within the active site of PNP and that the positioning of two hydroxyl groups was critical for picomolar activity. SerMe-ImmH (10, K(d) = 5.2 pM) was shown to be orally available in mice with a long biological residence time on blood PNP.

Synthesis of the four 1-(1-deoxy-D-pentitol-1-yl)thymines and conformational properties of the acyclic sugar chain

Acetylated D-pentose diethyl dithioacetals were coupled by way of 1-bromo-1-ethylthio derivatives with 2,4-bis(trimethylsilyl)thymine to afford diastereomeric pairs of acyclic-sugar nucleoside analogues bearing a thymin-1-yl and an ethylthio group at C-1. Free-radical desulfurization by the action of tributylstannane removed the ethylthio group to afford the corresponding acetylated 1-(1-deoxy-d-pentitol-1-yl)thymines and subsequently the free title compounds in the arabino, lyxo, ribo, and xylo series. Conformations of the intermediates and products were studied in detail and the final products were evaluated for their potential as agents active against plant viruses and rice blast fungus.