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Methanolysia of amicetin (I) yielded, besides cytimidine (II),*sa the methyl glycosides (VI) of a neutral sugar, amicetose (VII), and of an amino sugar, amoaamine (IX). Periodate fission of the 2,4-dinitrophenylhydrazone of amicetose (VIII) gave acetaldehyde and a derivative of succindialdehyde, leading to structure VI1 for the neutral sugar. Various degradations of amosamine and its derivatives were conducted and the results showed the amino mgar to be IX. Evidence is presented for the mode of linkage of amosamine, amicetose, and cytimidine in amicetin shown in structure I.(1) Parke, Davis and Co.,

A number of 5'-(O-acyl) derivatives of 9-beta-D-arabinofuranosyladenine (ara-A, VIRA-A) (2a-k) were prepared by direct acylation of the parent nucleoside 1 in pyridine-N,N-dimethyliformamide. These compounds, designed as prodrugs for 1, offer a range of solubilities and lipophilicities indicating for several examples improved solubility and the potential for improved membrane transport over 1. All are resistant to deactivation by adenosine deaminase. Of special interest is the 5'-(O-valeryl) derivative 2d that shows a marked increase in antiviral activity over 1.

A common property of many antibiotics which transcends chemical structural relationships is that of being inactivated by means of cysteine and certain related substances. It was suggested that possibly the fundamental mode of action of certain classes of antibiotics involves their ability to interfere with the normal function of sulfhydryl groups in bacterial metabolism.1Recently, Hauschka, Toennies and Swain2 have observed a similar behavior with A",9-hexeno-5-lactone and Geiger and Conn3 have explained the antibacterial action of clavacin, penicillic acid and a number of a,ß-unsaturated ketones on a similar basis. The latter investigators observed the disappearance of cysteine sulfhydryl groups in the presence of the antibacterial agents and, although no reaction products were isolated, there is evidence available in the literature showing that unsaturated ketones and acids are capable of adding RSH across the double bond,4-7 the RS group, as a rule, becoming attached to the carbon farthest from the ketone or carboxyl group even when the double bond is not ,ß-to the carbonyl group.8

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