Project description:Given the prevalence of the indole nucleus in biologically active compounds, the direct C3-functionalization of 2,3-disubstituted indoles represents an important problem. Described is a general, high-yielding method for the palladium-catalyzed beta-allylation of carba- and heterocycle fused indoles, including complex natural product substrates.
Project description:Trichloroacetimidates function as effective electrophiles for the selective C3-alkylation of 2,3-disubstituted indoles to provide 3,3'-disubstituted indolenines. These indolenines are common synthetic intermediates that are often utilized in the synthesis of complex molecules. Effective reaction conditions utilizing Lewis acid catalysts have been determined, and the scope of the reaction with respect to indole and imidate reaction partner has been investigated. This chemistry provides an alternative to base promoted and transition metal catalyzed methods that are more commonly utilized to access similar indolenines.
Project description:A general method for the synthesis of 2,3-disubstituted indoles is described. The key feature of this method is the amination of aromatic C-H bonds via FeCl(2)-catalyzed ring opening of 2H-azirines. The method tolerates a variety of functional groups such as Br, F, NO(2), OMe, CF(3), OTBS, alkenes, and OPiv. The method can also be extended to synthesize azaindoles.
Project description:A diastereo- and enantioselective CuH-catalyzed method for the preparation of highly functionalized indolines is reported. The mild reaction conditions and high degree of functional group compatibility as demonstrated with substrates bearing heterocycles, olefins, and substituted aromatic groups, renders this technique highly valuable for the synthesis of a variety of cis-2,3-disubstituted indolines in high yield and enantioeselectivity.
Project description:A de novo synthesis of a benzene ring allows for the preparation of a diverse range of heterocycles including indoles, benzofurans, benzothiophenes, carbazoles, and dibenzofurans from simple heteroaryl propargylic esters using a unified carbonylative benzannulation strategy. Multiple substituents can be easily introduced to the C4-C7 positions of indoles and related heterocycles.
Project description:The indole scaffold will continue to play a vital role in the future of drug discovery and agrochemical development. Regioselective direct arylation of indoles on the benzenoid moiety is a challenging task due to the inherent reactivity of the C2 and C3 positions. Here, we have developed an effective strategy for the regioselective direct arylation of indoles at the C7 position with (hetero)aryl bromides by the rational design of a directing group. The key to the high selectivity and reactivity of this method is the appropriate selection of a class of directing groups, N-PR2 (R = t Bu and c Hex), that are easily removed in the presence of the Wilkinson's catalyst. Using the present method as a key step, formal synthesis of marine alkaloid dictyodendrin B has also been demonstrated.
Project description:A catalytic, enantioselective method for the C-H functionalization of indoles by diazo compounds has been achieved. With catalytic amounts of Rh(2)(S-NTTL)(4), the putative Rh-carbene intermediates from α-alkyl-α-diazoesters react with indoles at C(3) to provide α-alkyl-α-indolylacetates in high yield and enantioselectivity. From DFT calculations, a mechanism is proposed that involves a Rh-ylide intermediate with oxocarbenium character.
Project description:Palladium-catalyzed oxidative annulations between phenols and alkenylcarboxylic acids produced a library of benzofuran compounds. Depending on the nature of the substitution of the phenol precursor, either 2,3-dialkylbenzofurans or 2-alkyl-3-methylene-2,3-dihydrobenzofurans can be synthesized with excellent regioselectivity. Reactions between conjugated 5-phenylpenta-2,4-dienoic acids and phenol gave 3-alkylidenedihydrobenzofuran alkaloid motifs while biologically active 7-arylbenzofuran derivatives were prepared by starting from 2-phenylphenols. More interestingly, selective incorporation of deuterium from D2O has been discovered, which offers an attractive one-step method to access deuterated compounds.
Project description:Herein, we report the synthesis of C3,C4-disubstituted indoles via the palladium/norbornene cooperative catalysis. Utilizing N-benzoyloxy allylamines as the coupling partner, a cascade process involving ortho-amination and ipso-Heck cyclization takes place with ortho-substituted aryl iodides to afford diverse indole products. The reaction exhibits good functional group tolerance, in addition to tolerating a removable protecting group on the indole nitrogen. Divergent reactivity has been observed using the allylamine coupling partner containing more substituted olefins. Construction of the core framework of mitomycin has also been attempted with this strategy.