No abstract

No abstract

Thirteen sugar derivatives of N-alkyl-N-nitrosourea have been prepared as follows. The reaction of a sugar amine with alkyl isocyanate gives a sugar derivative of N-alkylurea. When the product is treated with sodium nitrite in aqueous acetic acid, it gives the N-alkyl-N-nitrosourea derivative.

No abstract

Some derivatives of dolastatin 16, a depsipeptide natural product first obtained from the sea hare Dolabella auricularia, were synthesized through second-generation synthesis of two unusual amino acids, dolaphenvaline and dolamethylleuine. The second-generation synthesis enabled derivatizations such as functionalization of the aromatic ring in dolaphenvaline. The derivatives of fragments and whole structures were evaluated for antifouling activity against the cypris larvae of Amphibalanus amphitrite. Small fragments inhibited the settlement of the cypris larvae at potent to moderate concentrations (EC50 = 0.60-4.62 μg/mL), although dolastatin 16 with a substituent on the aromatic ring (24) was much less potent than dolastatin 16.