Reaction of Alkyl 2-Bromoalkanoates with Zinc and Arylglyoxales

Methyl 2-bromo-2-methylpropionate reacts with zinc and arylglyoxals under conditions of Reformatsky reaction in ether-HMPA mixture to afford 1-aryl-4,4,8,8-tetramethyl-2,6-dioxabicyclo[3.3.0]octane-3,7-diones in 68-85% yield. Methyl 2-bromopropionate reacts with zinc and 4-bromophenylglyoxal in the same way giving the bicyclic product in 28% yield. The bromination of 1-(4-tolyl)-4,4,8,8-tetramethyl-2,6-dioxabicyclo[3.3.0]octane-3,7-dione with bromosuccinimide results in successive replacement of hydrogens in the tolyl moiety by bromine. The calculation of formation enthalpy for stereoisomers of compounds obtained in AM1 approximation predicts the highest stability for chair-type conformation with eclipsed position of substituents at C¹ and C⁵ atoms.     

A Chemical Study of Burley Tobacco Flavour (Nicotiana tabacum L.) VII. Identification and synthesis of twelve irregular terpenoids,related to solanone,including 7,8-dioxabicyclo[3.2.1]octane and 4,9-dioxabicyclo[3.3.1]nonane derivatives

Twelve novel constituents isolated from Burley tobacco condensate by semi-preparative GLC. have been identified as (E)-3,4-epoxy-5-isopropyl-nonane-2,8-dione ( A ), exo-(1-methyl-4-isopropyl-7,8-dioxabicyclo[3.2.1]oct-6-yl)methyl ketone ( B ), exo-1-(1-methyl-4-isopropyl-7,8-dioxabicyclo[3.2.1]oct-6-yl)-ethanol ( C ), (E)-5-isopropyl-8-hydroxy-8-methyl-non-6-en-2-one ( D ), (E)-5-isopropyl-6,7-epoxy-8-hydroxy-8-methyl-nonan-2-one ( E ), endo-2-(1-methyl-4-isopropyl-7,8-dioxabicyclo[3.2.1]oct-6-yl)-propan-2-ol ( F ), 3,3,5-trimethyl-8-isopropyl-4,9-dioxabicyclo[3.3.1]nonan-2-ol ( G ), (E)-5-isopropyl-non-3-ene-2,8-diol ( H ), 5-isopropyl-nonane-2,8-diol ( I ), (E)-5-isopropyl-8-hydroxy-non-6-en-2-one ( J ), 5-isopropyl-8-hydroxy-nonan-2-one ( K ), and (E)-3-isopropyl-6-methyl-hepta-4,6-dien-1-ol ( L ). Compounds A–K were synthesized from norsolanadione ( 2 ), and compound L from 2-isopropyl-5-oxo-hexanal ( 15 ). The relative configuration of the bicyclic internal acetals B, C, F, G and their δ-keto-epoxide precursors A and E is discussed. All these Burley tobacco flavour components belong to a growing family of metabolites structurally related to solanone ( 1 ). They are believed to arise from the breakdown of cembrene-type precursors.     

Photochemische reaktionen von übergansmetall-olefinkomplexen: III. [4 + 6]-cycloaddition konjugierter diene an hexacarbonyl-μ-η6:6(-1,1′-bi(2,4,6-cycloheptatrien-1-yl)dichrom(O)

UV irradiation of hexacarbonyl-μ-η^6:6-1,1′-bi(2,4,6-cycloheptatrien-1-yl)dichromium(O) (I) in THF in the presence of 1,3-butadiene (A), E-1,3-pentadiene (B) and EE-2,4-hexadiene (C) causes preferentially a twofold [4 + 6]-cycloaddition and formation of the hexacarbonyl-μ-2–5 : 8.9-η-2′–5′ : 8′,9′-η-11,11′-bi(bicyclo-[4.4.1]undeca-2,4,8-trien-11-yl)dichromium(O) complexes (IVA–IVC). Partial decomplexation after the first [4 + 6]-cycloaddition yields isomeric tricarbonyl-2–5:8,9-η- (IIA–IIC) and tricarbonyl-2′–7′-η-{11-(2′,4′,6′-cycloheptatrien-1′-yl)bicyclo[4.4.1]undeca-2,4,8-triene}chromium(O) complexes (IIIA–IIIC). With 2,3-dimethyl-1,3-butadiene (D) mainly dicarbonyl-2–6 : 2′–4′-η-{1-(2′,3′-dimethyl-3′-buten-1′,2′-diyl)-7-(8″,9″-dimethylbicyclo[4.4.1]undeca-2″, 4″,8″-trien-11″-yl)cyclohepta-3,5-dien-2-yl}chromium(O) (VD) besides small amounts of pentacarbonyl-μ-2–6 : 2′–4′-η-2″–7″-η-{1-(2′,3′-dimethyl-3′-buten-1′,2′-diyl)-7-(2″, 4″,6″-cycloheptatrien-1″-yl)cyclohepta-3,5-dien-2-yl}dichromium(O) (VID) and tricarbonyl-2′-7′-η-{11-(2′,4′,6′-cycloheptatrien-1′-yl)-8,9-dimethyl-bicyclo[4.4.1]undeca-2,4,8-triene}-chromium(O) (IIID) is obtained. VD adds readily CO to yield tricarbonyl-2–5 : 8,9-η-11,11′-bi(8,9-dimethyl-bicyclo[4.4.1]undeca-2,4,8-trien-11-yl)chromium(O) (VIID). Finally D adds to VID under formation of pentacarbonyl-μ-2–6 : 2′–4′-η-2″–5″ : 8″,9″-η-{1-(2′,3′-dimethyl-3′-buten-1′,2′-diyl)-7-(8″,9″-dimethyl-bicyclo[4.4.1]- undeca-2″,4″,8″-trien-11″-yl)cyclohepta-3,5-dien-2-yl}dichromium(O) (VIIID). From IVA–IVC the hydrocarbon ligands (IXA–IXC) can be liberated by P(OCH₃)₃ in good yields. The structures of the compounds IIA–IXC were determined by IR     

Five bicyclo[3.3.0]octa‐2,6‐dienes

A series of five compounds containing the bicyclo[3.3.0]octa‐2,6‐diene skeleton are described, namely tetramethyl cis,cis‐3,7‐dihydroxybicyclo[3.3.0]octa‐2,6‐diene‐2,4‐exo,6,8‐exo‐tetracarboxylate, C₁₆H₁₈O₁₀, (I), tetramethyl cis,cis‐3,7‐dihydroxy‐1,5‐dimethylbicyclo[3.3.0]octa‐2,6‐diene‐2,4‐exo,6,8‐exo‐tetracarboxylate, C₁₈H₂₂O₁₀, (II), tetramethyl cis,cis‐3,7‐dimethoxybicyclo[3.3.0]octa‐2,6‐diene‐2,4‐exo,6,8‐exo‐tetracarboxylate, C₁₈H₂₂O₁₀, (III), tetramethyl cis,cis‐3,7‐dimethoxy‐1,5‐dimethylbicyclo[3.3.0]octa‐2,6‐diene‐2,4‐exo,6,8‐exo‐tetracarboxylate, C₂₀H₂₆O₁₀, (IV), and tetramethyl cis,cis‐3,7‐diacetoxybicyclo[3.3.0]octa‐2,6‐diene‐2,4‐exo,6,8‐exo‐tetracarboxylate, C₂₀H₂₂O₁₂, (V). The bicyclic core is substituted in all cases at positions 2, 4, 6 and 8 with methoxycarbonyl groups and additionally at positions 3 and 7 with hydroxy [in (I) and (II)], methoxy [in (III) and (IV)] or acetoxy [in (V)] groups. The conformations of the methoxycarbonyl groups at positions 2 and 4 are exo for all five compounds. Each C₅ ring of the bicyclic skeleton is almost planar, but the rings are not coplanar, with dihedral angles of 54.93 (7), 69.85 (5), 64.07 (4), 80.74 (5) and 66.91 (7)° for (I)–(V), respectively, and the bicyclooctadiene system adopts a butterfly‐like conformation. Strong intramolecular hydrogen bonds exist between the –OH and C=O groups in (I) and (II), with O...O distances of 2.660 (2) and 2.672 (2) Å in (I), and 2.653 (2) and 2.635 (2) Å in (II). The molecular packing is stabilized by weaker C—H...O(=C) interactions, leading to dimers in (I)–(III) and to a chain structure in (V). The structure series presented in this article shows how the geometry of the cycloocta‐2,6‐diene skeleton changes upon substitution in different positions and, consequently, how the packing is modified, although the intermolecular interactions are basically the same across the series.     

Synthesis of New Fused and Spiro Heterocyclic Systems from 3,5‐Pyrazolidinediones

4‐Bromo‐1‐phenyl‐3,5‐pyrazolidinedione 2 reacted with different nucleophilic reagents to give the corresponding 4‐substituted derivatives 3–8 . The cyclized compounds 9–11 were achieved on refluxing compounds 3 , 4 or 6_a in glacial acetic acid or diphenyl ether. 4,4‐Dibromo‐1‐phenyl‐3,5‐pyrazolidinedione 12 reacted with the proper bidentates to give the corresponding spiro 3,5‐pyrazolidinediones 13–15 , respectively. The 4‐aralkylidine derivatives 16_a‐c , were subjected to Mannich reaction to give Mannich bases 17_a‐c‐22_a‐c , respectively. 4‐(p‐Methylphenylaminomethylidine)‐1‐phenyl‐3,5‐pyrazolidinedione 23 or 4‐(p‐methylphenylazo)‐1‐phenyl‐3,5‐pyrazolidinedione 29 were prepared and reacted with active nitriles, cyclic ketones and N,S‐acetals to give pyrano[2,3‐c]pyrazole, pyrazolo[4′,3′:5,6]pyrano[2,3‐c]pyrazole, spiropyrazole‐4,3′‐pyrazole and spiropyrazole‐4,3′‐[1,2,4]triazolane derivatives 24–34 , respectively.     

Electronic structure of a metal-organic copper spin-1/2 molecule: bis(4-cyano-2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II)

The metal-organic molecule bis(4-cyano-2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II) (Cu(CNdpm)2) (C24H36N2O4Cu, Cu(II)) is a copper spin-1/2 system with a magnetic moment of 1.05 +/- 0.04 muB/molecule, slightly smaller than the 1.215+/-0.02 muB/molecule for the larger size copper spin-1/2 system C36H48N4O4Cu.C4H8O (bis(4-cyano-2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II) 4,4'-bipyridylethene-THF). There is generally good agreement between photoemission from vapor-deposited thin films of the C24H36N2O4Cu on Cu(111) and Co(111) and model calculations. Although this molecule is expected to have a gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, the molecule remains surprisingly well screened in the photoemission final state.     

The mannich reaction in the synthesis of N,S-containing heterocycles 4. Aminomethylation of 6-amino-3,5-dicyano-1,4-dihydropyridine-2-thiolates: A convenient regioselective route to 3,5,7,11-tetraazatricyclo[7.3.1.02,7]tridec-2-ene derivatives

Treatment of N-methylmorpholinium 4-R-6-amino-3,5-dicyano-1,4-dihydropyridine-2-thiolates (R = 2-ClC₆H₄ and 2-MeOC₆H₄) with primary amines in the presence of an excess of formaldehyde gave 13-R-8-thioxo-3,5,7,11-tetraazatricyclo[7.3.1.0^2,7]tridec-2-ene-1,9-dicarbonitrile derivatives in high yields (66–95%). In a similar way, aminomethylation of 3-R-10-amino-7,11-dicyano-9-aza-3-azoniaspiro[5.5]undeca-7,10-diene-8-thiolates (R = Me and Et) afforded 1′-alkyl-8-thioxospiro[3,5,7,11-tetraazatricyclo[7.3.1.0^2,7]tridec-2-ene-13,4′-piperidine]-1,9-dicarbonitriles in 43–91% yields. Alternatively, these compounds were obtained by multicomponent cyclocondensation of N-alkylpiperidin-4-ones, cyanothioacetamide, primary amines, and aqueous formaldehyde. The starting 3-R-10-amino-7,11-dicyano-9-aza-3-azoniaspiro[5.5]undeca-7,10-diene-8-thiolates were prepared by a new method from N-alkylpiperidin-4-ones and cyanothioacetamide. The structure of 5,11-bis(4-ethoxyphenyl)-13-(2-methoxyphenyl)-8-thioxo-3,5,7,11-tetraazatricyclo[7.3.1.0^2,7]tridec-2-ene-1,9-dicarbonitrile was examined by X-ray diffraction analysis. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1014–1022, May, 2007.     

Sequential thermal rearrangements of syn-9-vinyl-bicyclo[6.1.0]-nona-2,4,6-triene

The title compound 1-syn at 65°C undergoes a cascade of thermal rearrangements to yield tetracyclo[5.4.0.0.^2,11O^4,10]undeca-5, 8-diene (5). The kinetics for the isomerization of the intermediate bicyclo(4.3.2]-undeca-2,4,7,10-tetraene (3) have been measured.     

Studies on Cage Compounds. Synthesis of 8,11-Diazenediyl-4,4-Dimethoxy-2,3,5,6-Tetrachloropentacyclo[5.4.0.02,5.03,10.05,9]Undecane

The title compound ( 7 ) was synthesized in six steps from 1,8,9,10-tetrachloro-11,11-dimethoxy-endo-tricyclo[6.2.1.0^2,7]undeca-4,9-diene-3,6-dione ( 4 ) in an overall yield of 36%. The key intermediate, 1,8,9,10-tetrachloro-11,11-dimethoxy-endo-tricyclo-[6.2.1.0^2,7]undeca-3,5,9-triene ( 12 ), obtained from 4 by reduction, mesylation and then 1,4-elimination, was allowed to react with diethyl azodicarboxylate to afford the Diels-Alder adduct 16 . Photochemical closure of 16 , followed by hydrolysis and decarboxylation, gave the title compound. The title compound failed to give either the homopentaprismanone derivative 3 or the diene 9 by the photochemical or thermal elimination of molecular nitrogen.     

Rearrangement of O,O’-bis(2-benzylideneaminophenyl) phenylphosphonite into 1,6,7-triphenyl-3,4:9,10-dibenzo-2,11-dioxa-5,8-diaza-1-phosphatricyclo[6.3.0.01,5]undeca-3,9-diene

Keeping of O,O’-bis(2-benzylideneaminophenyl) phenylphosphonite in a CCl4 solution for 50 days resulted in its spontaneous rearrangement into 1,6,7-triphenyl-3,4:9,10-dibenzo-2,11-dioxa-5,8-diaza-1-phosphatricyclo[6.3.0.01,5]undeca-3,9-diene, a representative of spirophosphoranes with P–N bonds.     

Ritter reaction. Synthesis of 1-substituted 3,3,7,9-tetramethyl-2-azaspiro[4.5]deca-6,9-dien- and -1,6,9-trien-8-ones and 7-methoxy-3,3,6,8-tetramethyl-3,4-dihydroisoquinolines

1-(4-Methoxy-3,5-dimethylphenyl)-2-methylpropan-1-ol reacted with nitriles [MeSCN, PhCN, MeCN, EtOC(O)CH₂CN] in the presence of concentrated sulfuric acid to give both 1-R-3,3,7,9-tetramethyl-2-azaspiro[4,5]deca-6,9-dien- and -1,6,9-trien-8-ones and 1-R-7-methoxy-3,3,6,8-tetramethyl-3,4-dihydroisoquinolines. The reaction with 3,4-dimethoxyphenylacetonitrile afforded 10,11-dimethoxy-1,3,6,6-tetramethyl-1,5,6,12b-tetrahydrodibenzo[d,f]indole-2,8-dione. Three-component condensation of 2-methoxy-1,3-dimethylbenzene with isobutyraldehyde and nitriles led to the formation of spirocyclic systems and 3,4-dihydroisoquinoline derivatives in lower yield.     

The Reaction of Patchoulol with Lead Tetraacetate,a Regiospecific Fragmentation

Patchoulol (1) forms 2,2,6,8-tetramethylbicyclo [5.3.1]undec-7-en-3-one (5) with lead tetraacetate. This ketone undergoes acid-catalyzed cyclization to 2,6,6,10-tetramethyltricyclo [5.3.1.0^1,5]undec-9-en-5-ol (10) , and is reduced to 2 stereoisomeric alcohols with lithium aluminium hydride. One of these alcohols 8 is readily dehydrated with cyclization to 2,6,6,10-tetramethyltricyclo [5.3.1.0^1,5]undec-9-ene (12) and a double bond isomer 13 , longer treatment with acid resulting in a Wagner-Meerwein rearrangement to a mixture of two 1,3,7,7-tetramethyltricyclo [6.2.1.0^2,6]-undecenes ( 19 and 20 ), isomeric with β-patchoulene ( 23 ). The other alcohol 7 with p-toluenesulfonic acid forms the cyclic ether, 1,3,7,7-tetramethyl-11-oxatricyclo-[4.4.1.1^2,8]dodecane ( 15 ).     

A bicyclic conjugated diene monomer,tetrahydroindene, for cationic polymerization and a novel alicyclic hydrocarbon polymer with heat resistance

This study was directed toward the cationic polymerization of tetrahydroindene (i.e., bicyclo[4.3.0]‐2,9‐nonadiene), a bicyclic conjugated diene monomer, with a series of Lewis acids, especially focusing on the synthesis of high‐molecular‐weight polymers and subsequent hydrogenation for novel cycloolefin polymers with high service temperatures. EtAlCl₂ or SnCl₄ induced an efficient and quantitative cationic polymerization of tetrahydroindene to afford polymers with relatively high molecular weights (number‐average molecular weight > 20,000) and 1,4‐enchainment bicyclic main‐chain structures. The subsequent hydrogenation of the obtained poly(tetrahydroindene) with p‐toluenesulfonyl hydrazide resulted in a saturated alicyclic hydrocarbon polymer with a relatively high glass transition (glass‐transition temperature = 220 °C) and improved pyrolysis temperature (10% weight loss at 480 °C). The new diene monomer was randomly copolymerized with cyclopentadiene at various feed ratios in the presence of EtAlCl₂ to give novel cycloolefin copolymers, which were subsequently hydrogenated into alicyclic copolymers with variable glass‐transition temperatures (70–220 °C). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6214–6225, 2006     

Reactivity of an N,N‐Chelated Germylene Toward Substituted Alkynes,Alkenes, and Allenes

Treatment of N,N‐chelated germylene [(iPr)₂NB(N‐2,6‐Me₂C₆H₃)₂]Ge ( 1 ) with ferrocenyl alkynes containing carbonyl functionalities, FcC≡CC(O)R, resulted in [2+2+2] cyclization and formation of the respective ferrocenylated 3‐Fc‐4‐C(O)R‐1,2‐digermacyclobut‐3‐enes 2 – 4 [R = Me ( 2 ), OEt ( 3 ) and NMe₂ ( 4 )] bearing intact carbonyl substituents. In contrast, the reaction between 1 and PhC(O)C≡CC(O)Ph led to activation of both C≡C and C=O bonds producing bicyclic compound containing two five‐membered 1‐germa‐2‐oxacyclopent‐3‐ene rings sharing one C–C bond, 4,8‐diphenyl‐3,7‐dioxa‐2,6‐digermabicyclo[3.3.0]octa‐4,8‐diene ( 5 ). With N‐methylmaleimide containing an analogous C(O)CH=CHC(O) fragment, germylene 1 reacted under [2+2+2] cyclization involving the C=C double bond, producing 1,2‐digermacyclobutane 6 with unchanged carbonyl moieties. Finally, 1 selectively added to the terminal double bond in allenes CH₂=C=CRR′ giving rise to 3‐(=CRR′)‐1,2‐digermacyclobutanes [R/R′ = Me/Me ( 7 ), H/OMe ( 8 )] bearing an exo‐C=C double bond. All compounds were characterized by ¹H, ¹³C{¹H} NMR, IR and Raman spectroscopy and the molecular structures of 3 , 4 , 5 , and 8 were established by single‐crystal X‐ray diffraction analysis. The redox behavior of ferrocenylated derivatives 2 – 4 was studied by cyclic voltammetry.     

Consequences of Substitution in the Photoelectron Spectra of [2, 2]Paracyclophanes: Separation of ‘through-space’ and ‘through-bond’ interactions as a consequence of fluorosubstitution

The PE. spectra of [2, 2]paracyclophane ( 1 ), 4-amino[2, 2]paracyclophane ( 2 ) and 1, 1, 2, 2, 9, 9, 10, 10-octafluoro[2, 2]paracyclophane ( 3 ) are presented. The bands corresponding to ejection of the photoelectron from the five highest occupied π-orbitals have been assigned. The ‘observed’ orbital energies (i.e. the negative ionization potentials) are discussed in terms of ‘through space’ and ‘through-bond’ interactions between the semi-localized π-orbitals ( e_1g ) of the benzene moieties and the C, C-σ-orbitals of the ethylene bridges. The PE. spectrum of 3 shows that the fluorine-induced lowering of the C, C-σ-orbital energy effectively ‘turns-off’ the ‘through-bond’ interaction. The resulting pattern of the first four bands confirms the assignment given for 1 . Finally the band shifts induced by an amino group in position 4 are again in agreement with this assignment. Attention is drawn to the phenomenon of ‘orbital switching’ as a consequence of substitution in loosely coupled systems such as 1 .     

Divergent synthesis and chemical reactivity of bicyclic lactone fragments of complex rearranged spongian diterpenes

The synthesis and direct comparison of the chemical reactivity of the two highly oxidized bicyclic lactone fragments found in rearranged spongian diterpenes (8-substituted 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one and 6-substituted 7-acetoxy-2,8-dioxabicyclo[3.3.0]octan-3-one) are reported. Details of the first synthesis of the 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one ring system, including an examination of several possibilities for the key bridging cyclization reaction, are described. In addition, the first synthesis of 7-acetoxy-2,8-dioxabicyclo[3.3.0]octanones containing quaternary carbon substituents at C6 is disclosed. Aspects of the chemical reactivity and Golgi-modifying properties of these bicyclic lactone analogs of rearranged spongian diterpenes are also reported. Under both acidic and basic conditions, 8-substituted 2,7-dioxabicyclo[3.2.1]octanones are converted to 6-substituted-2,8-dioxabicyclo[3.3.0]octanones. Moreover, these dioxabicyclic lactones react with primary amines and lysine side chains of lysozyme to form substituted pyrroles, a conjugation that could be responsible for the unique biological properties of these compounds. These studies demonstrate that acetoxylation adjacent to the lactone carbonyl group, in either the bridged or fused series, is required to produce fragmented Golgi membranes in the pericentriolar region that is characteristic of macfarlandin E.     

Synthesis of Tetracyclo[6.2.2.23,6.02,7]tetradeca-4,9,11,13-Tetraene

The title hydrocarbon 3, a C₁₄H₁₄ tetracyclic tetraene of C_2v-symmetry, was synthesized by new routes starting from 1,8,9,10-tetrachloro-11,11-dimethoxytricyclo[6.2.1.0^2,7]undeca-3,5,9-triene (1). The Diels-Alder cycloaddition of 1 with 2-chloroacrylyl chloride, a ketene equivalent, followed by subsequent reduction, dechlorination and deacctalization afforded the ketol 12 as a key intermediate. Elaboration of target compound 3 was carried out by either the method of ring enlargement of 12 or (better) the route of Diels-Alder reaction of decarbonylated 12 with trans-1,2-bis(phenylsulfonyl)ethcnc, an acetylene equivalent, to give trienol 17, followed by dehydration. Upon irradiation, 3 underwent intercyclic [2 + 2]-addition to caged hexacyclic diene 4. At 120°C, 3 decomposed into barrelene and benzene quantitatively.     

NMR experiments on acetals. 300 MHz spectrum and conformational aspects of the 1-aza-4,6-dioxabicyclo[3.3.0]octane system

Complete analyses of the 300 MHz ¹H NMR spectra of 1-aza-4,6-dioxabicyclo[3.3.0]octane ( 1a ), the 5-Me- ( 1b ), and both the cis- and trans-3,5-diMe- derivatives ( 1c and 1t ), as well as most of the corresponding methiodides are reported. Spectral data suggest probable conformations to be 11 ( 1a , 1b and 1c ) and 13 ( 1t ), respectively. The corresponding methiodides adopt slightly different forms, having flattened N? C-2? C-3 moieties ( 12 for 2a , 2b and 2c ).     

Synthesis of a C(9)—C(13) fragment of acutiphycin from levoglucosan

Alkylation of (1R,2R,5R)-2-benzenesulfonyl-6,8-dioxa-bicyclo[3.2.1]octan-3-one, which is accessible from levoglucosan, afforded (1R,2R,5R)-2-benzenesylfonyl-2,4,4-trimethyl-6,8-dioxabicyclo[3.2.1]octan-3-one. This was further converted into (1S,2R,3S,5R)-2,4,4-trimethyl-6,8-dioxabicyclo[3.2.1]octan-3-ol representing the C9—C13 fragment of acutiphycin molecule.     

A Photochemical Approach to a Potential Precursor of the Bicyclo [6.4.0] Dodecane Ring System of Taxane Diterpenes

The intermolecular [2+2] photocycloaddition of dimedone 6 and 1-acetoxy-2-methyl-5-dioxolan-1-hexene 7 followed by alkaline treatment, gave the 1,5,5,11-tetramethyl-7-dioxolan bicyclo [4,3,2]-4-decen-2,3-dione 12, and the 1,5,5-trimethyl-3-hydroxy-7-dioxolan bicyclo [5,4,1] dodecan-2,11-dione 13.