Topic
Annulation
About: Annulation is a research topic. Over the lifetime, 10152 publications have been published within this topic receiving 189701 citations.
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TL;DR: An application of the phosphine-catalyzed [4 + 2] annulation in the formal synthesis of alstonerine and macroline is reported, which formed the D ring of the target indole alkaloids.
181 citations
TL;DR: The catalytic C-H coupling method employs cheaply available phenols and alcohols, exhibits a broad substrate scope, tolerates carbonyl and amine functional groups, and liberates water as the only byproduct.
Abstract: A well-defined cationic Ru–H complex catalyzes the dehydrative C–H alkylation reaction of phenols with alcohols to form ortho-substituted phenol products. Benzofuran derivatives are efficiently synthesized from the dehydrative C–H alkenylation and annulation reaction of phenols with 1,2-diols. The catalytic C–H coupling method employs cheaply available phenols and alcohols, exhibits a broad substrate scope, tolerates carbonyl and amine functional groups, and liberates water as the only byproduct.
180 citations
TL;DR: The development of the annulation with a wide substrate scope provided a unique opportunity to evaluate photophysical properties of a series of aryl- and heteroaryl-annulated[a]carbazoles, which were found to emit purple to green light in the visible region.
Abstract: Treatment of 2-aryl- and 2-heteroarylindoles with propargyl ethers in the presence of a catalytic amount of indium nonafluorobutanesulfonate [In(ONf)3] gave aryl- and heteroaryl-annulated[a]carbazoles in good yields. The synthetically attractive feature is reflected by its applicability to a wide range of 2-aryl- and 2-heteroarylindoles. In the annulation reaction, propargyl ethers act as C3 sources (HC≡C−CH2OR). Among these, two carbon atoms are incorporated into the product as members of a newly constructed aromatic ring and the remaining carbon atom forms a methyl group on the aromatic ring, where the methyl group is always located next to the C3 position of the indole nucleus. The methyl group can be easily removed through SeO2 oxidation followed by decarbonylation with RhCl(CO)(PPh3)2−Ph2P(CH2)3PPh2 as a catalyst. The new annulation strategy is applicable also to symmetrical dimers such as bithiophene and bifuran derivatives. Mechanistic studies suggest that the first step is addition reaction initia...
179 citations
TL;DR: Revitalization by oxygen: A rhodium(III)-catalyzed oxidative CH/NH activation/annulation sequence provided access to a variety of substituted 1,2-benzothiazine derivatives from readily available NH-sulfoximines and alkynes.
Abstract: Revitalization by oxygen: A rhodium(III)-catalyzed oxidative CH/NH activation/annulation sequence provided access to a variety of substituted 1,2-benzothiazine derivatives from readily available NH-sulfoximines and alkynes (see scheme; Cp*=C5 Me5 ). The oxidation system consisted of molecular oxygen in combination with a catalytic amount of Fe(OAc)2 .
179 citations
TL;DR: Benzophosphole construction was achieved through the Ag(I) -mediated dehydrogenative annulation of phenylphosphine oxides with internal alkynes in a process involving C�C and CP bond formation with perfect regioselectivity.
Abstract: Benzophosphole construction was achieved through the Ag(I) -mediated dehydrogenative annulation of phenylphosphine oxides with internal alkynes in a process involving CC and CP bond formation. A wide range of asymmetrical phenylacetylenes could be employed and the reactions proceeded with perfect regioselectivity. Moreover, the annulation could be conducted even at room temperature when a Mn(III) promoter was used in place of Ag(I) .
177 citations