Bislactonization

As in the synthesis of (+)-26 (Scheme 8), treatment of (-)-27 with chromic acid accomplishes oxidative scission of the carbon-carbon double bond, and provides (-)-26 after an intramolecular bislactonization reaction (Scheme 16). By analogy to the conversion of 50 into 51 (see Scheme 8), treatment of (-)-26 with ammo-... 

Lipases CA, BC, and PF catalyzed the polymerization of ethylene dode-canoate and ethylene tridecanoate to give the corresponding polyesters. The enzyme origin affected the polymerization behaviors in using lipase BC catalyst, these bislactones polymerized faster than e-CL and DDL, whereas the reactivity of these cyclic diesters was in the middle of e-CL and DDL in using lipase CA. 

A. P. Rauter, F. Piedade, T. Almeida, R. Ramalho, M. J. Ferreira, R. Resende, J. Amado, H. Pereira, J. Justino, A. Neves, F. V. M. Silva, and T. Canda, Sugar bislactones by one-step oxidative dimerisation with pyridinium chlorochromate versus regioselective oxidation of vicinal diols, Carbohydr. Res., 339 (2004) 1889-1897. 

The oxidation of alkenedioic acids 98-100 with HTIB leads to the stereospecific production of respective bislactones (86TL5437) (Eqs. 23-25). 

The bislactone 36 is the first example of a cluster opened C70 derivative [38]. It was formed by the spontaneous oxidation of PhgC7Q (35) in air (Scheme 11.8). 

Preparation of bioactive podolactones via a new Pd-catalysed bislactonization reaction. Synthesis of oidiolactone C. Barrero, A. F. Quflez del Moral, J. F. Cuerva, J. M. Cabrera, E. Jimenez-Gonzalez, D. Tetrahedron Lett. 2000, 41, 5203-5206. 

Bislactones 34 were prepared similarly from the corresponding methylene bisketolactones.75,76... 

Dicarbonyl 4//-pyran derivatives can be converted to 1,4-dihydro-pyridines. 3,5-Diketones 86 (R = R1 = H R2 = H, Ph), 13, and bislactone 34b afforded appropriate azaheterocycles 571,2 572,37 and 573.76 More complex 1,4-dihydropyridines 574 were synthesized analogously.68,69... 

These furanes can be used for synthesis of bislactones or y-hydroxybutenolides by reaction with aldehydes or ketones in the presence of TiCl4 (equations II and III). 

FuranonesS The first step in a simplified synthesis of bislactones involves condensation of an a-halo aldehyde (1) and potassium ethyl malonate (2) in benzene- water in the presence of tetra-n-butylammonium bromide. The furanone 3 is converted to the hislactone 4 by bromination followed by treatment with HBr. The product is a precursor to df-avcnaciolide (5), a fungicide from Aspergillus arenaceous. 

Thallium(lII) trifluoroacetate is a versatile oxidant for organic compounds [55, 56, 57] It reacts with alkenes at room temperature to form oxiranes, ketones, and 1,2 diols [55] Usually these oxidations are accompanied by cyclizations and rearrangements The reaction of thallium(III) trifluoroacetate with substituted cinnamic acids results in instantaneous oxidative dimerization leading to bislactone lignans, which belong to a naturally occurring family of compounds [56] (equation 26)... 

Cyclopentenones. Reaction of the Fittig bislactone 2 with methyllithium results in the substituted cyclopentenone 3 in moderate yield. This product on oxidative decarboxylation gives methylenomycin B (4).2... 

Corey EJ, Gross AW (1980) Bislactonization of Unsaturated Diacids using Lead Tetraacetate. Tetrahedron Lett 21 1819... 

Oxidative dimerization of cinnamic acids Cinnamic acid itself is stable to TTFA in the presence of BF3 etherate but 4-alkoxycinnamic acids are converted by these two reagents in TFA-CH2CI2 to fused bislactones by a nonphenolic oxidative dimerization (equation I). A few natural products of this type are known. 

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