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: Alkyne tethered benzamides undergo rhodium(III)-catalyzed intramolecular annulations to give tricyclic isoquinoline derivatives in good yields.
Abstract: Alkyne tethered benzamides undergo rhodium(III)-catalyzed intramolecular annulations to give tricyclic isoquinoline derivatives in good yields. DFT calculations suggest that the reaction mechanism involves a migratory insertion of the alkyne into the rhodium–nitrogen bond of the rhodacycle intermediate that results from the initial C–H activation. This contrasts with the pathway proposed for intermolecular cases, which considers an insertion into the rhodium–carbon instead of the rhodium–nitrogen bond. The annulation is also effective with acrylamides; and, while anilides fail to participate in the process, naphthylamides do undergo the intramolecular annulation, albeit the chemoselectivity is different than for the intermolecular reactions.
119 citations
TL;DR: An efficient synthesis of N-methyl-3-chalcogeno-indoles has been developed via iodine-mediated electrophilic annulation reactions of 2-alkynylaniline derivatives with disulfides or diselenides in moderate to excellent yields and it is noteworthy that iron can promote the reaction.
Abstract: An efficient synthesis of N-methyl-3-chalcogeno-indoles has been developed via iodine-mediated electrophilic annulation reactions of 2-alkynylaniline derivatives with disulfides or diselenides In the presence of iodine and iron, a variety of 2-alkynylanilines selectively underwent the electrophilic annulation with numerous disulfides or diselenides leading to the corresponding 3-sulfenylindoles and 3-selenenylindoles in moderate to excellent yields It is noteworthy that iron can promote the reaction
119 citations
TL;DR: A variety of substituted coumarins have been prepared in good yields by the palladium-catalyzed coupling of o-iodophenols with internal alkynes and 1 atm of carbon monoxide.
119 citations
118 citations
TL;DR: Coupling of (S)-2-N,N-di-tert-butoxycarbonyl-5-oxopentanoate, derived from L-glutamic acid, with ortho-haloanilines provides a rapid access to the ring-A-substituted tryptophans in good to excellent yields.
Abstract: One-pot synthesis of indoles by a palladium-catalyzed annulation of ortho-haloanilines and aldehydes has been developed. Coupling of ortho-iodoaniline with aldehyde is realized under mild ligandless conditions [Pd(OAc)2, DABCO, DMF, 85 °C], whereas X-Phos is found to be the ligand of choice for coupling reactions involving ortho-chloroanilines/ortho-bromoanilines and aldehydes. A variety of ortho-haloanilines with different electronic properties are suitable substrates, and aldehydes including chiral ones participated in this reaction without racemization. Coupling of (S)-2-N,N-di-tert-butoxycarbonyl-5-oxopentanoate, derived from l-glutamic acid, with ortho-haloanilines provides a rapid access to the ring-A-substituted tryptophans in good to excellent yields.
118 citations