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An effective, general protocol for the Diversity-Oriented Synthesis (DOS) of 2,4,6-trisubstituted piperidine congeners has been designed and validated. The successful strategy entails a modular approach to all possible stereoisomers of the selected piperidine scaffold, exploiting Type II Anion Relay Chemistry (ARC), followed in turn by intramolecular S(N)2 cyclization, chemoselective removal of the dithiane moieties and carbonyl reductions. 相似文献
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[formula: see text] A synthetic scheme for the selective functionalization of all-cis (rccc) resorcinarene platform at the "lower rim" was developed. Self-folding and self-complementary cavitands were prepared for molecular recognition and self-assembly, bearing functionality at remote sites. These molecules promise applications on solid support and as polymeric capsules. 相似文献
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An effective one-flask multicomponent linchpin coupling protocol employing the concept of anion relay chemistry (ARC) was developed. This concept calls for addition of an anion (5) to an epoxide (6), bearing on a distal carbon a trialkyl silyl group and an anion stabilizing group (ASG), to furnish upon epoxide ring opening oxyanion 7. Addition of HMPA or other polar solvents to trigger a solvent controlled 1,4-Brook rearrangement then leads to a new distal anion (8), which in turn is available to react with a variety of second electrophiles. 相似文献
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-Hydrindanediones (1, 3, and 15) have been synthesized in short steps through stereoselective introduction of vinylsilane units onto the cycloalkenones 5 or 10 followed by AgBF4-mediated internal acylation of the vinylsilane moiety. 相似文献
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The [1,5]-Brook rearrangement proceeds efficiently in a series of hydroxyl dithiane substrates with sodium and potassium bases; less effective are lithium bases. That the mode of silyl migration is intramolecular was demonstrated by a crossover experiment. Finally, the tricomponent anion relay chemistry (ARC) coupling tactic was demonstrated employing the [1,5]-Brook rearrangement. 相似文献
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A convenient synthesis of carbanucleosides, with both enantiomers equally accessible, is reported. The key step is a tandem linchpin cyclization process to give access to substituted carbafuranose derivatives having the correct relative stereochemistry for subsequent nucleobase introduction with inversion of configuration at C1. This was illustrated by the synthesis of 2',3'-dideoxycarbathymidine via a convergent nucleobase introduction and of 2',3'-dideoxy-6'-hydroxycarbauridine via a linear nucleobase introduction. Both methods relied on Mitsunobu chemistry, and the first example of the Mukaiyama modification of the Mitsunobu reaction involving nucleobases as nucleophiles is reported. 相似文献
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Jha SC Lorch M Lewis RA Archibald SJ Boyle RW 《Organic & biomolecular chemistry》2007,5(12):1970-1974
A calix[4]phyrin-(1,1,1,1) substituted with a 4-isothiocyanatophenyl group has been synthesised and used to attach the macrocycle to a solid support. The NCS group can also be used to further functionalise the calix[4]phyrin-(1,1,1,1) by reaction with amines and amino acids. Stability constants for anion binding by the calix[4]phyrin-(1,1,1,1) are reported and these show a clear ability to differentiate F(-) and HSO(4)(-) from Cl(-), Br(-), I(-) which can be detected by both NMR and UV-visible spectroscopy. 相似文献
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An efficient, six-step stereocontrolled total synthesis of the antifungal agent strobilurin B is reported and was based on a convergent bi-directional coupling featuring a hetero-bis-1,4-metallated pentadiene system as the linchpin. 相似文献
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Pieter Claes 《Tetrahedron》2010,66(35):7088-7096
3-Substituted pentalongin derivatives possessing an acetal function at C-1 were synthesized by cyclization of acylmethylnaphthoquinones. The latter naphthoquinones were prepared starting from 2-dioxolanylnaphthoquinone by means of both a stoichiometric and a catalytic method deploying various pyridinium ylids. 相似文献
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A short and efficient synthesis of the cytotoxic macrolide amphidinolide P is described. A remarkably chemo- and regioselective ruthenium-catalyzed alkene-alkyne coupling allows for a convergent synthesis and demonstrates that both enynes and beta-lactones are suitable coupling partners. This work also features a novel strategy for the preparation of macrolactones via intramolecular transesterification of beta-lactones. The target structure was prepared in 15 steps for the longest linear sequence and 10% overall yield, 24 steps total. 相似文献
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Nishida S Morita Y Ueda A Kobayashi T Fukui K Ogasawara K Sato K Takui T Nakasuji K 《Journal of the American Chemical Society》2008,130(45):14954-14955
We have demonstrated the features of curve-structured phenalenyl chemistry, for the first time. A phenalenyl-fused corannulene anion has been designed by the annelation of a six-memberd ring across peri-positions of corannulene and generated as a stable species in a degassed solution. The 1H and 13C NMR spectra have shown the highly symmetrical structure and high-field shifts of protons and carbons at the asterisked positions in the chemical structure, indicating the occurrence of large negative charge densities at these positions. These results well agree with the HOMO picture and the electrostatic potential surface, demonstrating the phenalenyl anion-type electronic structure is retained in the curved-surface pi-system. The calculated bowl-inversion barrier of the anion (11.3 kcal/mol) is larger than that of corannulene (9.2 kcal/mol) because of peri-annelation of the corannulene skeleton. The calculations of the barriers of the neutral radical (12.6 kcal/mol), radical dianion (8.1 kcal/mol), and trianion (5.4 kcal/mol) of the phenalenyl-fused corannulene have exhibited a stepwise flattening of the curvature with increase in negative charge. Therefore, we have revealed that the bowl-inversion barrier of the anion is governed by the setoff of the peri-annelation and negative charge effects. 相似文献
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General method for synthesis of functionalized macrocycles and catenanes utilizing "click" chemistry
A new protocol for efficient and high yield synthesis of functionalized macrocycles and catenanes has been developed using "click" chemistry in combination with Sauvage's metal template route to interlocked structures. The procedure involves introduction of terminal alkyne moieties on a symmetrical 2,9-diaryl-1,10-phenanthroline (phen) building block, followed by double-"click" ring closure using aryl 3,5-diazides in the presence of CuI, sodium ascorbate, the base DBU and a sulfonated phenanthroline ligand in an oxygen-free 7:3:1 ethanol/water/toluene mixture at 70 degrees C. Utilizing acetal and vinyl substituted diazides, the corresponding bistriazole/phen macrocycles, characterized spectroscopically, were obtained in 65-70% yield. Formation of a binary Cu(I) complex of the diethynylphen ligand followed by reaction with aryl 3,5-diazides using a modified procedure affords the corresponding difunctionalized catenane in one step in 85-92% yield. The initial catenanes obtained after workup are Cu-free. Reintroduction of Cu(I) using Cu(CH3CN)4+PF6- gives the metallocatenanes, whose spectral properties are identical to those of related (phen)2Cu(I) catenanes reported by Sauvage and co-workers. This methodology provides ready access to functionalized interlocked structures, which can be used as intermediates in the preparation of a variety of new materials, including compounds of interest as artificial photosynthetic systems. 相似文献
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Iodine-mediated cyclization of (Z)- and (E)-{=D}-ribohept-2-enonates and gave exclusively the β-ribofuranose and α-ribofuranose derivatives and , respectively. Cyclization of the (Z)- and (E)-2-heptene-1-ol derivatives and gave ribofuranose products ( and ) and a ribopyranose (), respectively. 相似文献
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Leo M.H. Leung Mark E. Light Vicky Gibson Bruno Linclau 《Tetrahedron: Asymmetry》2009,20(6-8):821-831
Enantiopure carbafuranose derivatives were synthesised via a linchpin carbacyclisation process starting from 1,4-bisepoxides. Both 2-deoxy and 2-deoxy-6-hydroxycarbafuranose derivatives were obtained, which were converted to suitably protected precursors for carbanucleoside synthesis. 相似文献
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《Tetrahedron letters》2014,55(50):6817-6820
Click chemistry reactions have recently attracted significant attention for several applications in biomaterials science. In addition microwave irradiation of aqueous solutions containing appropriate combinations of polymers is gaining increasing interests in the synthesis of sterile hydrogels without using monomers, eliminating so the need for removal of unreacted species. The combination of these two approaches promises to be a simple and efficient strategy to produce RGD functionalized hydrogels with a high degree of functionalization and appropriate physico-chemical properties. 相似文献
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Smith AB Hoye AT Martinez-Solorio D Kim WS Tong R 《Journal of the American Chemical Society》2012,134(10):4533-4536
The unification of Anion Relay Chemistry (ARC) with the Takeda and Hiyama palladium-mediated cross-coupling processes to provide aryl-aryl, alkenyl-aryl, and alkenyl-alkenyl coupled products by exploiting a common silicon-based transfer agent has been achieved. These results provide a practical solution for intermolecular cross-coupling of organolithium reagents without the problematic lithium-halogen exchange and/or undesired homocoupling that has kept organolithium cross-couplings from achieving the same level of utility asother palladium-mediated methods (e.g., Suzuki organoboron, Negishi organozinc, Stille organotin, Kumada organomagnesium, etc.). 相似文献
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Bin Ma 《Tetrahedron letters》2005,46(4):703-706
A highly stereoselective synthesis of the functionalized hydroazulene skeleton of portulal (1), has been achieved using the newly developed cobalt catalyzed [4+2+2] homo Diels-Alder chemistry. 相似文献