Synthesis of Cyclobuta[b]quinoxalines

Abstract

3-keto compound which reacts with hydrazine to give the hydrazone, which was isolated as acetate (14) (85 % yield; m.p. 132-135 "C, [a]: = +135 O, c = 0.7 in CHC13). The ai'locompound (9) eliminates the axial U-mesyl group from C-3, giving the 2,3-enoI 2-mesylate, whose further analogous reaction and acetylation affords a 3-deoxy-2-dose acetylhy-The gluco-and altro-compounds (10) and (11) cannot undergo trans-elimination. Thus, in these cases, nucleophilic substitution again becomes the reaction with hydrazine (at 140 O C , 5 h). The a-hydrazino-0-mesylates formed with inversion as primary products contain trans-hydrogen atoms and U-mesylate groups, so that elimination follows as a secondary reaction, leading to alkenylhydrazines which can be isolated, after acetylation, as rearranged deoxy-dose acetylhydrazones. Reaction of (10) and (11) in this way yields a mixture of (12) and (14), wherein (12) preponderates since nucleophilic attack on C-2 is apparently easier than on C-3. Transhydrazonization of (12) and (14) with benzaldehyde in weakly acidified dioxane solution makes accessible the 3-deoxy-2-ulose derivative (13) (53.7 % yield, m.p. 112-113 "C, [a]: = +93.8 O , c = 1.2 in CHC13), and the 2-deoxy-3-ulose derivative (15) (75 yield, m.p. 172 to 173 O C , [a]: = +129', c = 1.2 in CHC13[71).

Oxokohlenstoffe und verwandte Verbindungen, 31 [1]. 3-Antipyryl-4-hydroxy-cyclobutendion (Antipyrylsemiquadratsäure) und seine Derivate / Oxocarbons and Related Compounds, 31 [1]. 3-Antipyryl-4-hydroxy-cyclobutenedione (Antipyrylsemisquaric Acid) and its Derivatives

“…Ein vergleichbarer Ringschluss wurde bereits bei der Umsetzung von Phenylsemiquadratsäurechlorid mit o-Phenylendiaminen beobachtet [19].…”

4-Iminocyclobutenones: Synthesis and Building-Blocks of Aminohydroquinones and Annulated Quinolines

“…Thione derivatives have been prepared as such 9 or as thioacetals 10,11 and there are scattered reports on cyclobutenimines although no general synthesis is available. [12][13][14] The present study fills this gap and opens the door for a comparison of the cyclobutenone chemistry outlined in Scheme 1 with that of the nitrogen congeners.…”