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A series of di-(adenosin-N6-yl) alkanes (1b) - (1l) has been prepared by reaction of the appropriate diaminoalkanes with 6-chloro-9-β-D-(2,3,5-tri-O-acetyl)-ribofuranosyl-purine (2) followed by ammonolysis. Alternatively, an analogous reaction with 6-chloro-9-β-D-(2,3-O-isopropylidene)-ribofuranosylpurine (3) produced an intermediate which could be phosphorylated at the 5'-position prior to hydrolytic removal of the isopropylidene group. 4-(1,2,4-Triazolo)-1-(β-D-2,3,5-tri-O-acetyl ribofuranosyl)-2(1H)-pyrimidone (7) was an effective intermediate for the preparation of di-(cytidin-N4-yl) alkanes (8a), (8b), and (8c) from the appropriate diaminoalkanes. The longer chain di-(adenosin-N6-yl) alkanes are very effective inhibitors of adenosine kinase. In addition an approach to the di-(adenosin-N6-yl) alkanes is described which should allow tritium labelling of the alkyl chain.

The syntheses of eleven analogues of Cyclosporin are described; the analogues which contain (Me)Thr, (Me)Ser, Hyp and Dab at position-1 and Abu, Nva, Nle and Thr at position-2 were prepared by stepwise assembly of the undecapeptide fragments followed by cyclisation with a variety of reagents. The highest yields were obtained using the Castro reagent, and in the best case, (Hyp 1 ,Abu 2 ) cyclosporin, a yield of 65% was obtained.

A proton n.m.r. method has been used to monitor racemisation during the coupling of N -methylated amino acids by the diphenylphosphinic mixed anhydride procedure. No racemisation was observed when urethane protection was employed, but use of the benzoyl group led to extensive racemisation. The reagent was subsequently used for the assembly of several extensively N -methylated peptides.