Reactions of diazocyclopropane with hydrogenated and cyclopropanated levoglucosenone analogs

Abstract

Diazocyclopropane attacks the carbonyl group of 6,8 dioxabicyclo[3.2.1]octan 4 one or 7,9 dioxatricyclo[4.2.1.0 2,4 ]nonan 5 one, saturated derivatives of levoglucosenone, to form the corresponding stereoisomeric oxaspiropentanes. In the case of the strained tricyclononane, 5R isomer isomerizes under the reaction conditions into spiro fused cyclobutanone. For this ketone, the formation of homologation products, i.e., the respective regioisomeric spiro [8,10 dioxatricyclo[5.2.1.0 2,4 ]decane 6(5),1´ cyclopropan] 5(6) ones, is also observed.It is known 1-4 that diazocyclopropane generated by decomposition of N cyclopropyl N nitrosourea under the action of different bases reacts with unsaturated compounds containing an activated C=C bond, which allows introduction of spirocyclopropane fragments into molecules of heterocyclic compounds. Due to high reac tivity, diazocyclopropane reacts, like other diazoalkanes, with carbonyl compounds as well to form the respective oxaspiropentanes and homologation products of the ke tones. 5-8 Also the reactions of diazocyclopropane with unsaturated carbonyl compounds were described, but the known examples are limited to 3 acetoxypregna 5,16 dien 20 one and pregna 4,16 diene 3,20 dione 9,10 where the reactions with the carbonyl groups were ob served along with 1,3 dipolar addition to the C=C bond of ring D. Recently, we have shown 11 that diazocyclo propane generated in situ from N cyclopropyl N nitroso urea under the action of bases reacts selectively with either the C=C double bond of levoglucosenone to form 1 pyrazoline (K 2 CO 3 , CH 2 Cl 2 , 5 °C) or the carbonyl group with selective formation of the respective oxaspiropentane (MeONa/MeOH, -30 °C) depending on the reaction conditions.In continuation of the investigations into the reac tions of diazocyclopropane with ketones and aiming at synthesis of new optically active derivatives of 6,8 dioxabicyclo[3.2.1]octan 4 one with cyclopropane fragments in the molecule, we studied the reaction of diazocyclopropane with 6,8 dioxabicyclo[3.2.1]octan 4 one 12 and with a cyclopropane analog of levoglucos enone, 7,9 dioxatricyclo[4.2.1.0 2,4 ]nonan 5 one, ob tained by us earlier in three steps from levoglucosenone. 13 Results and DiscussionThe reaction of diazocyclopropane with 7,9 dioxa tricyclo[4.2.1.0 2,4 ]nonan 5 one (1) was carried out under the conditions analogous to those used in its reaction with levoglucosenone, 11 the decomposition of N cyclopropyl N nitrosourea (2) under the action of MeONa/MeOH at -30 °C in dichloromethane at a molar ratio of 1 and 2 equal to 1 : 2 was used for the generation of diazo cyclopropane. 1 H and 13 C NMR spectroscopic analysis of the reaction mixture revealed the presence of several compounds the main of which were oxaspiropentane derivative of 7,9 dioxatricyclo[4.2.1.0 2,4 ]nonane (3a) and spiro fused cyclobutanone 4b in the ratio ~2 : 1. Together with these compounds, the "cyclopropane homologation" products of ketone 1, regioisomeric spiro[8,10 dioxa tricyclo[5.2.1.0 2,4 ]decane 5(6),1´ cyclopro...

Oxidative and hydrolytic cleavage of cyclopropane and spirocyclobutane derivatives of 6,8-dioxabicyclo[3.2.1]octane, the products of transformation of levoglucosenone

“…C 10 H 12 6)). 13 C NMR (CDCl 3 ), δ: 6.5 (C(3)), 13.8 (C(2)), 15.1 (C(4)), 28.1 (C(4´)), 31.3 (C(3´)), 69.6 (C(8)), 70.4 (C(1)), 83.2 (C(5)), 102.3 (C(6)), 176.4 (C=O).…”

“…1 6)), the rest of the signals overlap with signals for the major isomer. 13 C NMR (CDCl 3 ), δ: 9.2 (C(3)), 9.4 (C(2)), 15.0 (C(4)), 26.8 (CH 2 (β)), 31.3 (CH 2 (α)), 39.9 (C(5)), 70.4 (C(8)), 70.5 (C(1)), 101.6 (C(6)), 179.2 (COOH).…”