2,3-Dihydro-4H-pyran and various 2-substituted 2,3-dihydro-4H-pyrans have been shown to react with certain 6-substituted purines in the presence of a catalytic amount of acid to give the corresponding 6-substituted-9-(tetrahydro-2-pyrany1)-purines. This reaction provides a new synthetic route to the preparation of valuable models of certain purine deoxynucleosides which possess significant antitumor activity. The tetrah ydropyran molecule greatly increases the s o hbility of purine derivatives in organic solvents and provides a useful blocking group which can be readily used to prevent undesirable side reactions due to the presence of the imidazole hydrogen. Acid hydrolysis regenerates the purine.( 5 ) The synthetic route employed in the synthesis of N-methylalloxan and of N-phenylalloxan start~ nlth the appropriate monosubrtituted urea and cyano.cetic-corboxyl-C'~ acid to yield RNH-CONHC*OCHsCN, which undergoes ring closure in the pruence of

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Quantum Chromodynamics (QCD) is an application area that requires access to large supercomputing resources and generates large amounts of raw data. The UK's national lattice QCD collaboration UKQCD currently stores and requires access to around five Tbytes of data, a figure that is growing dramatically as the collaboration's purpose built supercomputing system, QCDOC [

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