Abstract: Carbamic acid lactones of the formula ##STR1## wherein Y is H or alkyl of 1-4 carbon atoms and R.sub.2 and R.sub.

Abstract: Penicillins of the formula ##STR1## wherein X is O or S; Y is H or alkyl; Z is ##STR2## R.sub.1 is H or OH; and R.sub.2 and R.sub.3 each are H or wherein X is O or S; Y is H or alkyl; R.sub.2 and R.sub.3 each are H or taken together with the carbons to which they are attached form an aromatic six-membered carbocyclic or N-heterocyclic ring and alkyl, alkoxy, dialkylamino or halogen derivatives thereof are active against Gram-positive and Gram-negative bacteria.

Abstract: Tetracyclic compounds of the formula ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each are H or alkyl, R.sup.5 is H, F, Cl, Br, CF.sub.3, OH, alkyl, alkoxy, NO.sub.2, NH.sub.2, alkylamino, dialkylamino or acylamino and X is O, S, SO, SO.sub.2, NH, N-alkyl or N-acyl, alkyl and alkoxy in each case being of 1-3 carbon atoms and acyl in each case being of 1-4 carbon atoms, with the proviso that when R.sup.5 is methoxy and X is a sulfur atom, R.sup.5 is in the 8- or 9-position only, and their physiologically acceptable acid addition salts, possess broad spectrum antibacterial activity, including tetracycline-resistant Gram-positive and Gram-negative organisms.