7,14-Bis(4-methoxy­phen­yl)-11,11-dimethyl-1,4,10,12-tetra­oxa­dispiro­[4.2.5.2]penta­decane-9,13-dione

In the title compound, C27H30O8, the cyclo­hexane ring is in a chair conformation, while the five-membered ring adopts an envelope conformation. The 1,3-dioxane ring is oriented with respect to the benzene rings at dihedral angles of 53.38 (3) and 55.31 (3)°, while the dihedral angle between the benzene rings is 71.56 (3)°. In the crystal structure, inter­molecular C—H⋯O inter­actions link the mol­ecules into chains

In situ preparation of a multifunctional chiral hybrid organic-inorganic catalyst for asymmetric multicomponent reactions

[EN] A chiral mesoporous organosilica material incorporating a urea based-cinchona derivative and propylamine groups was prepared by a co-condensation method. The multisite solid catalyst efficiently promoted the asymmetric multicomponent reaction of aldehydes, malonates and nitromethane.This work was supported by the Spanish Government (Consolider Ingenio 2010-MULTICAT (CSD2009-00050) and MAT2011-29020-C02-01). P.G.-G. is grateful for a JAE-DOC contract from CSIC co-funded by the ESF. The Severo Ochoa program is thankfully acknowledged.García García, P.; Zagdoun, A.; Coperet, C.; Lesage, A.; Díaz Morales, UM.; Corma Canós, A. (2013). In situ preparation of a multifunctional chiral hybrid organic-inorganic catalyst for asymmetric multicomponent reactions. Chemical Science. 4(5):2006-2012. https://doi.org/10.1039/C3SC22310HS2006201245José Climent, M., Corma, A., & Iborra, S. (2012). Homogeneous and heterogeneous catalysts for multicomponent reactions. 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Brønsted-Acid-Catalyzed Asymmetric Multicomponent Reactions for the Facile Synthesis of Highly Enantioenriched Structurally Diverse Nitrogenous Heterocycles. Accounts of Chemical Research, 44(11), 1156-1171. doi:10.1021/ar2000343Huang, Y., Walji, A. M., Larsen, C. H., & MacMillan, D. W. C. (2005). Enantioselective Organo-Cascade Catalysis. Journal of the American Chemical Society, 127(43), 15051-15053. doi:10.1021/ja055545dEnders, D., Hüttl, M. R. M., Grondal, C., & Raabe, G. (2006). Control of four stereocentres in a triple cascade organocatalytic reaction. Nature, 441(7095), 861-863. doi:10.1038/nature04820Galzerano, P., Pesciaioli, F., Mazzanti, A., Bartoli, G., & Melchiorre, P. (2009). Asymmetric Organocatalytic Cascade Reactions with α-Substituted α,β-Unsaturated Aldehydes. Angewandte Chemie International Edition, 48(42), 7892-7894. doi:10.1002/anie.200903803Ramachary, D. B., Chowdari, N. S., & Barbas, C. F. (2003). Organocatalytic Asymmetric Domino Knoevenagel/Diels–Alder Reactions: A Bioorganic Approach to the Diastereospecific and Enantioselective Construction of Highly Substituted Spiro[5,5]undecane-1,5,9-triones. Angewandte Chemie International Edition, 42(35), 4233-4237. doi:10.1002/anie.200351916Ramachary, D. B., Anebouselvy, K., Chowdari, N. S., & Barbas, C. F. (2004). Direct Organocatalytic Asymmetric Heterodomino Reactions:  The Knoevenagel/Diels−Alder/Epimerization Sequence for the Highly Diastereoselective Synthesis of Symmetrical and Nonsymmetrical Synthons of Benzoannelated Centropolyquinanes. The Journal of Organic Chemistry, 69(18), 5838-5849. doi:10.1021/jo049581rRamachary, D. B., & Barbas, C. F. (2004). Towards Organo-Click Chemistry: Development of Organocatalytic Multicomponent Reactions Through Combinations of Aldol, Wittig, Knoevenagel, Michael, Diels-Alder and Huisgen Cycloaddition Reactions. 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(2006). Polystyrene-Supported Hydroxyproline:  An Insoluble, Recyclable Organocatalyst for the Asymmetric Aldol Reaction in Water. Organic Letters, 8(20), 4653-4655. doi:10.1021/ol061964jZamboulis, A., Rahier, N. J., Gehringer, M., Cattoën, X., Niel, G., Bied, C., … Man, M. W. C. (2009). Silica-supported l-proline organocatalysts for asymmetric aldolisation. Tetrahedron: Asymmetry, 20(24), 2880-2885. doi:10.1016/j.tetasy.2009.11.024Fan, X., Sayalero, S., & Pericàs, M. A. (2012). Asymmetric α-Amination of Aldehydes Catalyzed by PS-Diphenylprolinol Silyl Ethers: Remediation of Catalyst Deactivation for Continuous Flow Operation. Advanced Synthesis & Catalysis, 354(16), 2971-2976. doi:10.1002/adsc.201200887Wang, C. A., Zhang, Z. K., Yue, T., Sun, Y. L., Wang, L., Wang, W. D., … Wang, W. (2012). «Bottom-Up» Embedding of the Jørgensen-Hayashi Catalyst into a Chiral Porous Polymer for Highly Efficient Heterogeneous Asymmetric Organocatalysis. Chemistry - A European Journal, 18(22), 6718-6723. doi:10.1002/chem.201200753Riente, P., Yadav, J., & Pericàs, M. A. (2012). A Click Strategy for the Immobilization of MacMillan Organocatalysts onto Polymers and Magnetic Nanoparticles. Organic Letters, 14(14), 3668-3671. doi:10.1021/ol301515dShi, J. Y., Wang, C. A., Li, Z. J., Wang, Q., Zhang, Y., & Wang, W. (2011). Heterogeneous Organocatalysis at Work: Functionalization of Hollow Periodic Mesoporous Organosilica Spheres with MacMillan Catalyst. Chemistry – A European Journal, 17(22), 6206-6213. doi:10.1002/chem.201100072Bleschke, C., Schmidt, J., Kundu, D. S., Blechert, S., & Thomas, A. (2011). A Chiral Microporous Polymer Network as Asymmetric Heterogeneous Organocatalyst. Advanced Synthesis & Catalysis, 353(17), 3101-3106. doi:10.1002/adsc.201100674Rueping, M., Sugiono, E., Steck, A., & Theissmann, T. (2010). Synthesis and Application of Polymer-Supported Chiral Brønsted Acid Organocatalysts. Advanced Synthesis & Catalysis, 352(2-3), 281-287. doi:10.1002/adsc.200900746Kasaplar, P., Riente, P., Hartmann, C., & Pericàs, M. A. (2012). A Polystyrene-Supported, Highly Recyclable Squaramide Organocatalyst for the Enantioselective Michael Addition of 1,3-Dicarbonyl Compounds to β-Nitrostyrenes. Advanced Synthesis & Catalysis, 354(16), 2905-2910. doi:10.1002/adsc.201200526Wang, W., Ma, X., Wan, J., Cao, J., & Tang, Q. (2012). Preparation and confinement effect of a heterogeneous 9-amino-9-deoxy-epi-cinchonidine organocatalyst for asymmetric aldol addition in aqueous medium. Dalton Transactions, 41(18), 5715. doi:10.1039/c2dt12390hCancogni, D., Mandoli, A., Jumde, R. P., & Pini, D. (2012). Silicone-Supported Cinchona Alkaloid Derivatives as Insoluble Organocatalysts in the Enantioselective Dimerization of Ketenes. European Journal of Organic Chemistry, 2012(7), 1336-1345. doi:10.1002/ejoc.201101320Jumde, R. P., Mandoli, A., De Lorenzi, F., Pini, D., & Salvadori, P. (2010). 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Polyoxometalate-intercalated layered double hydroxides as efficient and recyclable bi-functional catalysts for cascade reactions

The polyoxometalate (POM) intercalated-layered double hydroxides (LDHs) have been widely used as heterogeneous catalysts. However, the application of POM-LDHs as bi-functional catalysts for cascade reaction has seldom been studied comparing with the noble metal-based catalysts. Herein, a series of POM-LDHs catalysts of Tris-LDH-X4(PW9)2 (X = Mn, Fe, Co, Ni, Cu and Zn) has been prepared; The efficacy of Tris-LDH-Zn4(PW9)2 as efficient bi-functional catalyst has been demonstrated for cascade reactions involving oxidation of benzyl alcohol to benzaldehyde followed by Knoevenagel condensation with ethyl cyanoacetate to produce benzylidene ethyl cyanoacetate. The combination of POM's redox/acidic sites and LDHs's basic sites led to a composite catalyst with excellent activity (99%) and selectivity (≥ 99%) under mild and soluble-base-free conditions. This work offer a new design strategy for the fabrication of efficient bi-functional catalysts for the promotion of one-pot cascade reactions

Intermolecular Gold(I)‐Catalyzed Alkyne Carboalkoxylation Reactions for the Multicomponent Assembly of β‐Alkoxy Ketones

A new gold(I)‐catalyzed multicomponent synthesis of β‐alkoxy ketones from aldehydes, alcohols, and alkynes is described. This atom economical synthesis was achieved through the use of the gold complex (SPhos)AuNTf 2 as a catalyst, and allows for the preparation of a diverse array of β‐alkoxy ketone products. Mechanistic studies illustrate that these reactions proceed via gold(I)‐catalyzed hydrolysis of the alkyne to an aryl ketone, which then undergoes an aldol reaction with an oxocarbenium ion generated in situ from the aldehyde and alcohol components.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94667/1/adsc_201200825_sm_miscellaneous_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/94667/2/3451_ftp.pd

Hydrophobically directed aldol reactions: polystyrene-supported L-proline as a recyclable catalyst for direct asymmetric aldol reactions in the presence of water

A simple synthetic methodology for the preparation of a polystyrene- supported L-proline material is reported, and this material has been used as catalyst in direct asymmetric aldol reactions between several ketones and arylaldehydes to furnish aldol products in high yields and stereoselectivities. Screening of solvents showed that these reactions take place only in the presence of water or methanol, at lower levels of conversion in the latter case. This solvent effect, coupled with the observed high stereoselectivities, has been ex- Introduction In the last decade organocatalysis has became a field of great interest.[1] Organocatalysts are metal-free small organic molecules that are able to function as efficient and selective catalysts for a large variety of enantioselective transformations. In this context, -proline and its derivatives have emerged as powerful organocatalysts.[2] -Proline can be regarded as the simplest “enzyme” and it has been successfully applied in many reactions, such as Robinson annulations,[3] aldol reactions,[4] Mannich reactions,[5] Michael reactions,[6] direct electrophilic α-aminations,[7] Diels– Alder reactions,[8] Baylis–Hillman reactions,[9] aza-Morita- Baylis–Hillman reactions,[10] α-selenenylation,[11] oxidation,[ 12] chlorination,[13] and others.[14] Among all these processes, -proline-mediated aldol reactions affording β-hydroxy ketones have been investigated in great depth. Indeed, the aldol reaction is one of the most important C–C bond-formation methods in organic synthesis.[ 15] Proline and its derivatives operate by bifunctional catalysis and play the role of a simplified version of the type I [a] Dipartimento di Chimica Organica “E.Paternò”, Università di Palermo, Viale delle Scienze, Pad. 17, 90128 Palermo, Italy Fax: +39-091-596825 E-mail: [email protected] © 2007 Wiley-VCH Verlag GmbH 4688 & Co. KGaA, Weinheim Eur. J. Org. Chem. 2007, 4688–4698 plained in terms of the formation of a hydrophobic core in the inner surface of the resin, whereas the hydrophilic proline moiety lies at the resin/water interface. Such a microenvironment both promotes the aldol reaction and increases the stereoselectivity. Recycling investigations have shown that this material can be reused, without loss in levels of conversion and stereoselectivity, for at least five cycles

Six-membered ring systems: with O and/or S atoms

A large variety of publications have emerged in 2012 involving O- and S-6- membered ring systems. The increasing number of reviews and other communica- tions dedicated to natural and synthetic derivatives and their biological significance highlights the importance of these heterocycles. Reviews on natural products involve biosynthesis and isolation of enantiomeric derivatives h12AGE4802i, biosynthesis, isolation, synthesis, and biological studies on the pederin family h12NPR980i and xanthones obtained from fungi, lichens, and bacteria h12CR3717i and on the potential chemotherapeutic value of phyto- chemical products and plant extracts as antidiabetic h12NPR580i, antimicrobial, and resistance-modifying agents h12NPR1007i. A more specific review covers a structure–activity relationship of endoperoxides from marine origin and their antitry- panosomal activity h12OBC7197i. New synthetic routes to naturally occurring, biologically active pyran derivatives have been the object of several papers. Different approaches have been discussed for the total synthesis of tetrahydropyran-containing natural products (")-zampanolide h12CEJ16868, 12EJO4130, 12OL3408i, (")-aspergillides A and B h12H(85)587, 12H(85)1255, 12TA252i, (þ)-neopeltolide h12JOC2225, 12JOC9840, 12H(85) 1255i, or their macrolactone core h12OBC3689, 12OL2346i. The total synthesis of bistramide A h12CEJ7452i and (þ)-kalihinol A h12CC901i and the stereoselec- tive synthesis of a fragment of bryostatin h12S3077, 12TL6163i have also been sur- veyed. Other papers relate the total synthesis of naturally occurring carbocyclic and heterocyclic-fused pyran compounds, such as (")-dysiherbaine h12CC6295i, penos- tatin B h12OL244i, Greek tobacco lactonic products, and analogues h12TL4293i and on the structurally intriguing limonoids andhraxylocarpins A–E h12CEJ14342i. The stereocontrolled synthesis of fused tetrahydropyrans was used in the preparation of blepharocalyxin D h12AGE3901i. Polyphenolic heterocyclic compounds have also received great attention in 2012. The biological activities and the chemistry of prenylated caged xanthones h12PCB78i, the occurrence of sesquiterpene coumarins h12PR77i, and the medicinal properties of the xanthone mangiferin h12MRME412i have been reviewed. An overview on the asymmetric syntheses of flavanones and chromanones h12EJO449i, on the synthesis and reactivity of flavones h12T8523i and xanthones h12COC2818i, on the synthesis and biosynthesis of biocoumarins h12T2553i, and on the synthesis and applications of flavylium compounds h12CSR869i has been discussed. The most recent developments in the synthesis and applications of sultones, a very important class of sulfur compounds, were reported h12CR5339i. A review on xanthene-based fluorescent probes for sensing cations, anions, bio- logical species, and enzyme activity has described the spiro-ring-opening approach with a focus on the major mechanisms controlling their luminescence behavior h12CR1910i. The design and synthesis of other derivatives to be used as sensors of gold species h12CC11229i and other specific metal cations h12PC823i have also been described. Recent advances related to coumarin-derived fluorescent chemosen- sors for metal ions h12COC2690i and to monitoring in vitro analysis and cellular imaging of monoamine oxidase activity h12CC6833i have been discussed. The study of various organic chromophores allowed the synthesis of novel dica- tionic phloroglucinol-type bisflavylium pigments h12SL2053i, and the optical and spectroscopic properties of several synthetic 6-aryldibenzo[b,d]pyrylium salts were explored h12TL6433i. Discussion of specific reactions leading to O- and S-membered heterocyclic compounds covers intramolecular radical cyclization h12S2475i and asymmetric enamine and dienamine catalysis h12EJO865i, oxa-Michael h12CSR988i and dom- ino Knoevenagel–hetero-Diels–Alder (hDA) reactions h12T5693i, and the versatility in cycloadditions as well as nucleophilic reactions using o-quinones h12CSR1050i. The use of specific reagents relevant to this chapter includes molecular iodine h12CEJ5460, 12COS561i, samarium diiodide–water for selective reductive transfor- mations h12CC330i, o-quinone methides as versatile intermediates h12CEJ9160i, InCl3 as catalyst h12T8683i, and gold and platinum p-acid mediated insertion of alkynes into carbon–heteroatom s-bonds h12S3401i. The remainder of this chapter discusses the most studied transformations on O- and S-6-membered heterocycles