| abstract |
A compound of formula I. wherein. R 0 is (1-5C) alkyl; R is hydrogen, formyl or trifluoroacetyl or. a more defined acyl group; each avog R 6 is, independently, hydrogen or lower alkyl; or. one avog R 6 is hydrogen or methyl and the other is a radical of the formula B.Y-, wherein. B is aryl or heteroaryl, which aryl or heteroaryl group may independently have one or more of the substituents indicated for A or an aryl or heteroaryl portion thereof; Y is a direct bond, methylene, ethylene or trans-vinylene; and. provided that no aliphatic carbon group is attached to more than one nitrogen or oxygen atom, except as part of a cyclic ketal or when the nitrogen atom carries a carbonyl group; or. when a compound of formula I is acidic or basic, a pharmaceutically acceptable salt thereof. |