Die Pyrazolo-cumarine 111 sowie deren Hydrazone wurden aus 3-Acetyl-4-hydroxy-cumarin (I) und dem entsprechenden Hydrazin erhalten. Bei der Behandlung von 3-Acetyl-cumarin rnit Hydrazin tritt Entacylierung unter Bildung von Salicylaldazin ein. -Die Einwirkung von Hydrazin auf o-Acetokhellinon (VI a) bzw. auf o-Aceto-visnaginon (VI b) fiihrt zu 4.7-Dirnethoxy-5-[3(oder 5)-methyM(oder 3)-pyrazolyll-cumaron (VII a) bzw. zu der entsprechenden 4-Methoxy-6-hydroxy-Verbindung VII b. -Die Pyrazolin-Derivate XIV (bzw. Isomere) werden leicht durch Einwirkung der entsprechenden Hydrazine auf Styryl-Derivate von I erhalten.

Cyclocondensation of the 6‐formyl‐7‐hydroxybenzopyran‐4‐ones (I) with cyanoacetic acid hydrazide (II), 1,1,3‐tricyano‐2‐aminoprop‐1‐ene (V), benzoylacetonitrile (VII), and malononitrile (XI) leads to the formation of the benzodipyrans (III), (VI), (VIII), (X), (XII), or (XIII).

Electrophilic cyclizations of a carbohydrate-derived δ-aminoalkene were studied. Iodocyclizations proceeded with moderate steric control to afford the D-gluco-configured piperidine as the major product. More extensive studies with mercuric salts resulted in the definition of new reaction conditions for aminomercuration that give higher, reversed stereoselection. The aminomercurations were also amenable to the use of a range of mercuric salts. These aminomercurations may be under chelation control with substrate allylic benzyloxy substituents. The configurations of the piperidine products were confirmed by elaboration of one bromomercurial to a known aminoalditol by oxydemercuration and hydrogenolysis.

Stereoselective Electrophilic Cyclizations of δ-Aminoalkenes Derived from Carbohydrates; Synthesis of Polyhydroxypiperidines.-Electrophilic cyclization of glucose-derived δ-aminoalkene (I) affords a mixture of D-gluco-and L-ido-configured polyhydroxypiperidines. Thus, iodocyclization of compound (I) with excess iodine or N-iodosuccinimide predominantly gives the D-gluco derivative (II) probably due to steric reasons. A similar result is obtained for the cyclization with mercury ions in aqueous THF solution furnishing D-gluco derivative (IV). In contrast, in the presence of excess mercury salt under non-aqueous conditions a change in stereoselectivity to the L-ido analogue (V) is observed, which is proposed to be a result of chelation control. -(HUEGEL, HELMUT M.; HUGHES, ANDREW B.; KHALIL, KHADIJEH; Aust.