2,2-Bis(nitromethyl)decane and 4-methyl-2,2-bis(nitromethyl)pentane reacted with α-bromolevoglucosenone in the presence of a base under ultrasonic treatment to give the corresponding cyclopenta-fused derivatives. Analogous reactions of 1,1-bis(nitromethyl)cycloalkanes with α-bromolevoglucosenone afforded spiro compounds.Reactions of α-bromo and α-iodo derivatives of conjugated enones with 2,2-dimethyl-1,3-dinitropropane lead to the formation of 2,3-cyclopentaannulation products containing a nitro group and geminal methyl groups in the cyclopentane fragment [1, 2]. Our attempts to obtain analogous products by treatment of α-bromolevoglucosenone with monosubstituted dinitro compounds or those having no other substituents than nitro groups were unsuccessful [3]. Nevertheless, with a view to extend the scope of application of this transformation, cyclopentaannulation of α-halo-substituted levoglucosenones can be achieved using other 2,2-disubstituted 1,3-dinitropropanes.By reacting the corresponding ketones with nitromethane in diethylamine we synthesized 2,2-bis(nitromethyl)decane, 4-methyl-2,2-bis(nitromethyl)pentane, 1,1-bis(nitromethyl)cyclohexane, 1,1-bis(nitromethyl)-cyclopentane, and 1,1-bis(nitromethyl)cyclododecane [4]. Ultrasonic treatment of a solution of α-bromolevoglucosenone and 2,2-bis(nitromethyl)decane in toluene in the presence of potassium carbonate and a catalytic amount of dicyclohexano-18-crown-6 afforded stereoisomeric tricyclic 3,4-cyclopentaannulation products IIa and IIb. Analogous reaction with 4-methyl-2,2-bis-(nitromethyl)pentane gave a mixture of epimers IIIa and IIIb (Scheme 1).The formation of diastereoisomers IIa/IIb and IIIa/IIIb suggests intermediacy of 2,2-disubstituted 1,3-dinitropropane dianions [2]; their addition to α-bromolevoglucosenone is influenced by steric interactions between the 1,6-anhydro bridge in the substrate and geminal substituents in the reagent. Unsuccessful cyclopentaannulation of α-halolevoglucosenone may be rationalized in terms of the possibility for charge delocalization in carbanions derived from 1,3-dinitro derivatives having no geminal substituents. Unlike isomer mixture IIIa/IIIb which was difficult to separate, epimers IIa and IIb can be readily separated by chromatography on silica gel. The reaction of α-bromolevoglucosenone (I) with cyclic dinitropropanes resulted in the formation of spiro compounds IV-VI in high yield (Scheme 1).The structure of compounds II-VI and configuration of new chiral centers therein were determined by 1 H and 13 C NMR spectroscopy, including HSQC, HMBC, and NOESY experiments performed with compounds IIa and IIb. In the 1 H NMR spectrum of isomer IIa the 2-H signal appeared as a doublet of doublets at δ 3.74 ppm ( 3 J 2, 3 = 9.9, 4 J 2, 5 = 2.7 Hz), and the 3-H proton resonated as a doublet at δ 4.91 ppm ( 3 J 2, 3 = 9.9 Hz). The corresponding couplings were confirmed by correlations observed in the HH COSY spectrum. The large value of 3 J 2, 3 (9.9 Hz) indicated trans orientation of 2-H and 3-H; taking into account the lac...
