- A General Method For The Coupling of Vinyl Stannanes
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The inter- and intra- copper mediated coupling of functionalised vinyl stannanes is reported.
- Beddoes Roy L.,Cheeseright, Timothy,Wang, Jingyang,Quayle, Peter
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- Synthesis of new fused and substituted benzo and pyrido carbazoles via C-2 (het)arylindoles
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In the course of a program aimed at designing new antitumor agents, we were interested in the synthesis of new substituted benzo and pyrido carbazoles. The synthesis was performed through an efficient four-step sequence from a 2-trimethylstannylindole derivative and via C-2 (het)arylindoles. The synthetic sequence was developed using two palladium mediated reactions including, at the end of the synthesis, a direct (het)arylannulation, which led to the desired heterocycles.
- Bourderioux, Aurélie,Kassis, Paméla,Mérour, Jean-Yves,Routier, Sylvain
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scheme or table
p. 11012 - 11019
(2009/04/11)
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- Palladium(0)-catalyzed heteroarylation of 2- and 3-indolylzinc derivatives. An efficient general method for the preparation of (2-pyridyl)indoles and their application to indole alkaloid synthesis
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Palladium(0)-catalyzed coupling of (1-(benzenesulfonyl)-2-indolyl)zinc chloride (1) and (1-(tert-butyldimethylsilyl)-3-indolyl)zinc chloride (6) with diversely substituted (alkyl, methoxy, methoxycarbonyl, nitro, hydroxy) 2-halopyridines gives the corresponding 2- and 3-(2-pyridyl)indoles [4 and 7 (or 8), respectively] in excellent yields. A series of other 3-(heteroaryl)indoles (pyrazinyl, furyl, thienyl, indolyl) have been similarly prepared from 6. The potential of some of these (2-pyridyl)indoles in alkaloid synthesis is demonstrated. Thus, from 2-(2-pyridyl)indole 4b, a new synthetic entry to the indolo[2,3-a]quinolizidine system, involving stereoselective hydrogenation of the pyridine ring with subsequent electrophilic cyclization upon the indole 3-position from an appropriately N(b)-substituted 2-(2-piperidyl)indole, is reported. For this purpose, Pummerer cyclizations have been extensively studied. Whereas the indole-unprotected sulfoxide 17 gives the corresponding indoloquinolizidine 19 in low yield and mainly undergoes an abnormal Pummerer cyclization that ultimately leads to sulfide 18, the N(a)-protected sulfoxides 24a and 24b afford the respective indoloquinolizidines 25a,b in 70% yield. On the other hand, the conversion of 3-(2-pyridyl)indole 8k into tetracyclic ketone 35 by stereoselective hydrogenation, followed by cyclization of the resulting all-cis-3-(2-piperidyl)indole 34, represents a formal synthesis of Strychnos alkaloids with the strychnan skeletal type (tubifoline, tubifolidine, 19,20-dihydroakuammicine). A similar conversion of 8j into nordasycarpidone constitutes a formal synthesis of the alkaloids of the uleine group. Reduction of nordasycarpidone leads to tetracycle 37, an advanced intermediate in a previous synthesis of tubotaiwine, a Strychnos alkaloid with the aspidospermatan skeletal type. Finally, piperidylindole 34 was transformed into tetracycle 41, an ABDE substructure of akuammiline alkaloids, by a sequence involving the skeletal rearrangement of an intermediate spiroindolenine as the crucial step.
- Amat, Mercedes,Hadida, Sabine,Pshenichnyi, Grigorii,Bosch, Joan
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p. 3158 - 3175
(2007/10/03)
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- An Efficient Synthesis of 2-(2-Pyridyl)indoles by Palladium(0)-catalyzed Heteroarylation
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A general method for the preparation of 2-(2-pyridyl)indoles based on the palladium(0)-catalyzed coupling of 1-(benzenesulfonyl)-2-indolylzinc chloride with 2-halopyridines is reported.
- Amat, Mercedes,Hadida, Sabine,Bosch, Joan
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p. 5005 - 5006
(2007/10/02)
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