Apparent endo-mode cyclic carbopalladation with inversion of alkene configuration via exo-mode cyclization-cyclopropanation rearrangement

Owczarczyk, Zbyslaw R.; Lamaty, Frédéric; Vawter, Edward J.; Negishi, E.

doi:10.1021/ja00051a069

Cited by 112 publications

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“…[15] This diene was not observed in the reactions of 6, 9, and 10; and here neither vinylcyclopropane 35, diene 36, or triene 37 Scheme 6. Cyclization of bromodienes 6 and 9Ϫ11: A: Pd(OAc) 2 nor cyclization products containing an acetoxy moiety were (10 mol-%), ligand (22 mol-%), base (210 mol-%), MeCN, 85°C, obtained. Another difference is the incomplete consump-5Ϫ6 h; B: Pd(OAc) 2 , PPh 3 , NEt 3 , MeCN, 85°C, 5.5 h; E ϭ CO 2 Me; tion of 27 even after reducing agents had been added (see for further details see Table 1 entries 3, 4, 5) while the other bromodienes, with a few exceptions, were completely converted into products.…”

Section: Cyclization Of 1-substituted 2-bromo-16-dienesmentioning

confidence: 97%

“…[2] We here report on palladium-cata-(10Ϫ25 mol-%) and silver carbonate in acetonitrile at 85°C, lyzed bicyclizations of 2-bromo-1,6-dienes and -1,6-enynes regardless whether methyl acrylate (28), to trap the cyclizawith certain substituents on the double bond and the triple tion product 31, was present or not. When potassium carbond to yield bicyclo[3.1.0]hexane derivatives.…”

Section: Introductionmentioning

confidence: 94%

“…Another difference is the incomplete consump-5Ϫ6 h; B: Pd(OAc) 2 , PPh 3 , NEt 3 , MeCN, 85°C, 5.5 h; E ϭ CO 2 Me; tion of 27 even after reducing agents had been added (see for further details see Table 1 entries 3, 4, 5) while the other bromodienes, with a few exceptions, were completely converted into products. To obtain more information about the mechanisms and to verify the (Z) configuration of acetate 40, 1,6-enyne acetate 42 (see below) was cyclized with 5 mol-% of Pd(dba) 2 , Mechanistic Considerations 10 mol-% of SbPh 3 , and 10 mol-% of acetic acid in [D 6 ]benzene [13] to give (E)-40 in 98% yield; the (Z) isomer was not In the 1-substituted 2-bromo-1,6-dienes 6, 9Ϫ11 with an acyloxy leaving group in an allylic position, the oxidative detected in the 1 H-NMR spectrum. (E)-40 decomposed completely when it was heated with palladium acetate, tri-addition to Pd 0 can occur both at the bromoalkenyl moiety to form an alkenylpalladium species and at the allylic posiphenylphosphane, and triethylamine in acetonitrile at 85°C for 6 h (conditions that lead selectively to 35, see entries 1, tion to form a η 1 -or η 3 -allyl complex.…”

Section: Cyclization Of 1-substituted 2-bromo-16-dienesmentioning

confidence: 99%

“…Since compound 37 obtained from (E)-40 in a separate experiment contained an unidentified by-product that correspond to 45 do not contain hydrogen atoms accessible for β-hydride elimination so that for them 3-exo-which was not observed with the bromodienes 6 and 11 as starting materials, a different mechanism might apply in trig (or some other) ring closure is the only accessible reaction channel. [2,5,18] those cases (Scheme 11), i.e. oxidative addition of the allyl ester moiety to Pd 0 , alkene insertion and β-hydride eliminComplexation of Pd II by the oxygen atoms in the acetate moiety of 45 might, in principle, slow down or prevent the ation would yield bromodiene 54, which should be dehydrobrominated rather easily (either directly by the action of the internal rotation required for β-hydride elimination so that dienophile in order to trap the expected Ϫ most probably The formation of the isomerized 1-acetoxymethyl-1,3-di-very sensitive Ϫ vinylallene as a stable DielsϪAlder adduct.…”

Section: Cyclization Of 1-substituted 2-bromo-16-dienesmentioning

confidence: 99%

“…Therefore added anion-capture reagents [33] such as hydride provided by sodium formate, Scheme 14. Cyclization of enyne carbonate 57: A: Pd(OAc) 2 should be able to compete with another species 65 or enyne (10 mol-%), PPh 3 (24 mol-%), MeCN, 85°C, 1.5 h; E ϭ CO 2 Me carbonate 57. Simply adding 2.0 equiv.…”

Section: Cyclization Of 1-substituted 16-enynesmentioning

confidence: 99%

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Palladium-Catalyzed Bicyclization of 2-Bromo-1,6-dienes and -1,6-enynes to 5-Membered-Ring-Annelated Vinylcyclopropane Derivatives

Steinig¹,

Meijere²

1999

Eur. J. Org. Chem.

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Palladium‐catalyzed cyclizations of the 2‐bromo‐1,6‐diene 6 with an acetoxymethyl substituent on the bromoalkenyl moiety did not only lead to the expected 1‐acetoxymethyl‐1,3‐diene 40 but also to the bicyclic vinylcyclopropane 35, the 1,3‐diene 36 and the triene 37 (a dendralene). All these compounds result from an initial 5‐exo‐trig cyclization of the 2‐bromo‐1,6‐diene. By proper choice of the reaction conditions (ligand, base, allylic leaving group) each of these compounds could be formed selectively. Small amounts (3–5%) of the isomerized 1‐acetoxymethyl‐1,3‐diene 38 and the 6‐endo product 39 were also isolated. With the acetoxymethyl substituent on the alkenyl moiety (compound 27) only the 1,4‐diene 44 was formed. The related 1,6‐enyne 57 with a methoxycarbonyloxymethylene substituent on the triple bond gave in 36% yield the 2,3‐bis(bicyclo[3.1.0]hex‐1‐yl)‐substituted 1,3‐butadiene 63, which can be regarded as a dehydrodimer of the vinylcyclopropane 35. The presumption that the formation of 63 involves the alkenylpalladium species 65 was supported by its successful inter‐ as well as intramolecular trapping with formate as a hydride source to yield the vinylcyclopropane 35. The reaction pathways leading to the vinylcyclopropane derivatives 35 and 63 have in common that an alkylpalladium species rather undergoes a 3‐exo‐trig cyclization than an internal rotation followed by a β‐hydride elimination.

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Section: Cyclization Of 1-substituted 2-bromo-16-dienesmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 94%

Section: Cyclization Of 1-substituted 2-bromo-16-dienesmentioning

confidence: 99%

Section: Cyclization Of 1-substituted 2-bromo-16-dienesmentioning

confidence: 99%

Section: Cyclization Of 1-substituted 16-enynesmentioning

confidence: 99%

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Palladium-Catalyzed Bicyclization of 2-Bromo-1,6-dienes and -1,6-enynes to 5-Membered-Ring-Annelated Vinylcyclopropane Derivatives

Steinig¹,

Meijere²

1999

Eur. J. Org. Chem.

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The IntramolecularHeck Reaction

Link

2002

Organic Reactions

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Since the discovery of the Heck reaction, the process has gained widespread acceptance within the synthetic community both as a practical tool and a research area. The intramolecular Heck reaction has enjoyed a similar renaissance, particularly within the last decade. The reaction has emerged as a reliable method for efficiently constructing small, medium, and large rings. Since the reaction occurs under mild and nearly neutral conditions, the functional group tolerance is high. Tandem reactions, which are initiated by intramolecular Heck reactions, have been developed allowing for multiple ring formations, cyclization and intermolecular coupling, and a multitude of other ever‐expanding possibilities. Furthermore, congested tertiary and quaternary centers can be efficiently constructed diastereoselectively or enantioselectively during the ring‐forming reaction. The numerous advances in reaction technology and capability have led to frequent application of the reaction in complex molecule synthesis and combinatorial library preparation. For the purposes of this chapter, the intramolecular Heck reaction is defined as the palladium[0]‐catalyzed intramolecular coupling of an aryl or alkenyl halide or perfluorosulfonate with an alkene, alkyne, allene, or arene. The mechanism of the Heck reaction is an active area of research. Precise mechanistic details vary substantially depending upon catalyst, substrate, additives, and reaction conditions. The introduction given here is designed to give the chemist a basic understanding of the currently accepted mechanisms to aid in the rational selection and optimization of reaction conditions. Application to total synthesis of natural products and intramolecular Heck reactions on polymer supports are discussed.

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Olefin Ring‐Closing Metathesis

Yet

2016

Organic Reactions

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The olefin ring‐closing metathesis reaction catalyzed by ruthenium and molybdenum complexes has been employed in the syntheses of carbocycles, heterocycles, supramolecular compounds, and in tandem metathesis reactions. Chiral ruthenium and molybdenum catalysts have provided high enantiomeric and diastereomeric excesses in ring‐closing metathesis reactions. Many of the unsuccessful medium‐ and large‐sized ring formations which were unsuccessful by traditional methods, such as the intramolecular Wittig, Horner–Wadsworth–Emmons, and Julia–Kocienski reactions, can now be formed by olefin ring‐closing metathesis reactions. Ring‐closing metathesis has been a key step and sometimes the only successful method for the synthesis of numerous natural products and drug discovery targets. The objective of this chapter is to provide an updated, comprehensive coverage of the literature of the olefin ring‐closing metathesis reaction and related processes. Key mechanistic points are summarized.

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Apparent endo-mode cyclic carbopalladation with inversion of alkene configuration via exo-mode cyclization-cyclopropanation rearrangement

Cited by 112 publications

References 0 publications

Palladium-Catalyzed Bicyclization of 2-Bromo-1,6-dienes and -1,6-enynes to 5-Membered-Ring-Annelated Vinylcyclopropane Derivatives

Palladium-Catalyzed Bicyclization of 2-Bromo-1,6-dienes and -1,6-enynes to 5-Membered-Ring-Annelated Vinylcyclopropane Derivatives

The IntramolecularHeck Reaction

Olefin Ring‐Closing Metathesis

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