Palladium‐Catalyzed Oligocyclizations of 2‐Bromoalka‐1,(n+m+1)‐dien‐(n+1)‐ynes – Influence of Tether Lengths and Substituents on the Outcome of the Reaction (Part II)

Schweizer, Stefan; Tokan, Wajdi M.; Parsons, Philip J.; Meijere, Armin de

doi:10.1002/ejoc.201000578

Cited by 12 publications

(2 citation statements)

References 34 publications

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“…Employing stoichiometric amounts of base gave a mixture of products 9 and 10 . Interestingly, the use of excess NaOH (50 % in H 2 O) and cetrimonium bromide (CTAB) in DCM also gave a mixture of 9 (31 %) and 10 (45 %) even after stirring for 72 h . This result indicates that the formal elimination of HBr to give the alkyne takes place from 2,3‐dibromopropene before the S N 2‐reaction and is much faster than elimination from ether 9 .…”

Section: Resultsmentioning

confidence: 98%

Synthesis of Raputimonoindoles A–C and Congeners

et al. 2019

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The first synthesis of raputimonoindole A from the tree Raputia praetermissa (Rutaceae) is reported, starting from indole‐5‐carbaldehyde. The key step is Braun′s diastereoselective Heck–Suzuki cascade that assembled the prenylated methylenetetrahydrofuran moiety. The unsubstituted indole enamine functionality was tolerated, and the absolute configuration of naturally occurring raputimonoindole A is assigned as (R,R). Raputimonoindole B was accessed by Ir‐catalyzed C–H activation/borylation followed by Suzuki–Miyaura cross‐coupling. Two biosynthetically related 5‐(dihydrofuran‐2‐yl)indole derivatives from R. simulans were synthesized by ring‐closing metathesis, and their absolute configurations were determined.

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Section: Resultsmentioning

confidence: 98%

Synthesis of Raputimonoindoles A–C and Congeners

et al. 2019

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“…The so-called Mizoroki-Heck reaction, i.e. , the palladium-catalyzed arylation or alkenylation of alkenes has been applied in a variety of new concepts [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]. In view of the steadily growing number of oligocyclic compounds with cyclopropyl moieties that show interesting biological activities [27,28,29], it is noteworthy and helpful that the highly reactive building block bicyclopropylidene 10 [30,31] can participate in various palladium-catalyzed cascade reactions to furnish complex skeletons containing cyclopropyl groups [17,18,19,20] A particularly high increase in molecular complexity can be achieved with sequential reactions starting with an intramolecular carbopalladation (the first step of a Heck reaction) of a 2-bromo-1-ene-6-yne and trapping of the formed reactive vinylpalladium halide intermediate by bicyclopropylidene 10 and subsequent transformations [32].…”

Section: Introductionmentioning

confidence: 99%

A Study of Palladium Catalyzed Intra/Intermolecular Cascade Cross Coupling/Cyclizations Involving Bicyclopropylidene

Demircan

2014

Molecules

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Abstract:The compounds [3-(2-Bromocyclohex-2-enyloxy)prop-1-ynyl]-tert-butyldimethylsilane 3, [4-(2-bromocyclohex-2-en-1-yloxy)but-2-yn-1-yloxy]tert-butyldimethylsilane 5 and dimethyl 2-(2-bromocyclohex-2-enyl)-2-(3-(tert-butyldimethylsilanyl)prop-2-ynyl)malonate 9 were prepared and subjected to palladium-catalyzed intra-intermolecular cascade cross couplings incorporating bicyclopropylidene 10 under two types of conditions. In the presence of Pd(OAc) 2 , PPh 3 and K 2 CO 3 in acetonitrile at 80 °C, the products were indene analogues, cross-conjugated tetraenes 11, 12 and 13, respectively. The corresponding spirocyclopropanated tricycle 16 in dimethylformamide at 110 °C was obtained, albeit in low yield (24%), and observed as an equimolar mixture of diastereomers, whereas 14, 15 were not fully isolated.

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Cross‐Coupling of Organyl Halides with Alkenes – The Heck Reaction

Bräse¹,

Meijere²

2013

Metal‐Catalyzed Cross‐Coupling Reactions and More

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The carbopalladation of an alkene by an organylpalladium halide is the essential step in one of the major contemporary metal-catalyzed C-C coupling reactions. About 45 years ago, a Japanese and an American group almost simultaneously designed and executed palladium-mediated coupling reactions of aryl and alkenyl halides with alkenes [1]. In subsequent investigations, Richard Heck and his group developed this reaction into a catalytic transformation and started to demonstrate its usefulness as well as its rather broad scope. The real push to utilize this powerful C-C-bondforming process, however, started only around the mid-1980s, and by now, an impressive number of publications have established the meanwhile so-called Heck reaction [2] 1) as an indispensable method in Organic Synthesis [3][4][5][6][7]. The universal recognition of the importance of the Heck reaction and the Negishi as well as the Suzuki coupling eventually won the Nobel Prize for Richard Heck along with Ei-ichi Negishi and Akira Suzuki in 2010. The applications of the Heck reaction range from the preparation of -functionalized and unfunctionalized -hydrocarbons, novel polymers, and dyes to new advanced enantioselective syntheses of natural products and biologically active nonnatural compounds. The more or less simultaneous developments of mechanistically related variants, namely, the Kumada, Suzuki, Stille, Hiyama, and Negishi coupling reactions (Chapters 12, 2, 3, 4, and 15, respectively) of metallated alkenes and arenes with aryl and alkenyl halides or the metal-catalyzed formation and cycloisomerization of enynes have drawn profit from the improvement of and mechanistic insights into the Heck reaction. This, of course, applies vice versa as well. Using only a catalytic amount of a palladium(0) complex or a precursor to a palladium species, the Heck reaction can bring about unprecedented structural changes, particularly when conducted intramolecularly. The full potential of this palladium-catalyzed process is still being further explored as demonstrated by a total of over 7000 publications in the past 40 years by 1) The alkynylation of aryl and alkenyl halides, frequently also considered as Heck reactions, is described in Chapter 6.

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Palladium‐Catalyzed Oligocyclizations of 2‐Bromoalka‐1,(n+m+1)‐dien‐(n+1)‐ynes – Influence of Tether Lengths and Substituents on the Outcome of the Reaction (Part II)

Cited by 12 publications

References 34 publications

Synthesis of Raputimonoindoles A–C and Congeners

Synthesis of Raputimonoindoles A–C and Congeners

A Study of Palladium Catalyzed Intra/Intermolecular Cascade Cross Coupling/Cyclizations Involving Bicyclopropylidene

Cross‐Coupling of Organyl Halides with Alkenes – The Heck Reaction

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