Low. et ( I / and crystallized from MeOH-H20 to yield 2.58 g (56% yield) of 10: mp 155-158"; nmr 6 5.64 (s, -CH=CH-). The mass spectrum showed the molecular ion a t m/e 703. Anal ( C~J H B~N O~~) C, H, N.Erythronolide A Oxime (11). A solution of 22.55 g (0.032 mol) of 10 in 1.5 1. of 3% HCl in MeOH was left a t room temperature for 21 hr. The MeOH was removed in ~'acu.0, EtOAc was added to the residue, and the solution was washed with dilute NaHC03. After drying, the solution was stirred briefly with charcoal, filtered, and concentrated to dryness. TIC revealed a major spot much slower moving than 10, several minor impurities, and two fast moving spots. Two crystallizations from (CH&CO-C&4 gave 9.64 g (69% yield) of pure 11: m p 236-239"; ir 1710 cm (lactone). The mass spectrum showed the molecular ion a t m j e 3,5-Diacetylerythronolide A Acetoxime (12). To 0.300 g (0.69 mmol) of 11 dissolved in 6 ml of anhydrous CJHJN was added 1.2 ml (12 mmol) of Ac2O and the solution was heated a t 70" for 16 hr. Solvent was removed using an oil pump, and the residue was dissolved in EtOAc and washed with dilute NaHC03. After drying, the solution was concentrated in vacuo to a solid residue. Crystallization from CHZC12-Et20 provided 0.302 g (77% yield) of pure 12: mp 234-235"; nmr 6 2.08, 2.11, and 2.20 (acetyl methyls); [a]Z5D -51.2" (c 0.97, CHC13). The mass spectrum showed the molecular ion a t m/e 559. Anal. (C27H45NOll) C, H, N. Erythronolide A (13). To a solution of 0.303 g (0.7 mmol) of 11 in 15 ml of MeOH was added 2.4 g (35 mmol) of NaN02 in 10 ml of H2O. After cooling in an ice bath, 35 ml (35 mmol) of 1 N HCI was added dropwise with stirring over 15 min. The solution was left at 3" for 5.5 hr and made basic with saturated NaHC03, and most of the MeOH was removed in L~C U O . The product was extracted with CHC13; the extract was dried and concentrated to a foam. Three crystallizations from ( C H~) Z C O -C~H~~ gave 0.115 g (40% yield) of pure 13: mp 172-173": ir 1712 (lactone) and 1688 cm (ketone); hmaxEfoH 290 nm ( e 37). The mass spectrum did not give a molecular ion peak but instead gave a peak for M--18at mle400. A n d . (C21H3808) C, H.A variety of Hantzsch-type dihydropyridines and related compounds have been prepared in the course of a structureactivity study of these potent hypotensive agents. The biological activity of one of these compounds (Ib) is described. This compound may be exerting its cardiovascular effects through a direct action on vascular smooth muscle. In comparative tests with hydralazine, a clinically used vasodilator, the effects of hydralazine tended to decrease over the treatment period, whereas Ib did not show this same tendency.

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A series of new 2-(2,3-dihydro-2-oxo-l,3,4-oxadiazol-5-yl) benzo heterocycles has been prepared. These compounds were tested as inhibitors of antigen-induced release of histamine (AIR) in vitro from rat peritoneal mast cells (RMC) and as inhibitors of IgE-mediated rat passive cutaneous anaphylaxis in the rat (PCA). Most of this new class of antiallergic agents showed good activity in the RMC assay. The most potent compound, 3-chloro-2-(2,3-dihydro-2-oxo-l,3,4-oxadiazol-5-yl)benzo[b]thiophene (6t), with an 1® value of 0.2 µ , is 15 times more potent than disódium cromoglycate (DSCG) in the RMC assay. Many compounds were orally active in the PCA test, and several of these compounds showed higher potency when given in this way to that shown by DSCG when given intraperitoneally.Since the introduction of disodium cromoglycate (DSCG, 1) for the treatment of asthma and allergy disease/ nui i merous compounds have been reported to be orally active antiallergic agents.1 2 Most of these compounds are carboxylic acids or derivatives thereof, such as esters3 or tetrazoles.4 There are, however, several exceptions, such as nivimedone (2),5 the pyran enamines 3,6 the tetracyclic pyrazole 4,7 and the benzoxepines 5.8 are able to determine, the benzo heterocyclic oxadiazolones (6) are new.14

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