Nucleophalic attacks on acetylenes

Dickstein, Jerome I.; Miller, Sidney I.

doi:10.1002/9780470771570.ch8

Cited by 40 publications

(20 citation statements)

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“…In the first insertion step of methyl 2-butynoate, the Ni−C bond of the benzyne complex reacts with the electron-poor β-carbon atom of the alkyne to give the nickelaindene 17 (Scheme ) in which the carboxylate-bearing carbon atom is bound to the metal atom. There is a direct analogy with the products of nucleophilic additions to alkynyl ketones or esters, for which an allenol resonance form is implicated . In the case of methyl and tert -butyl propiolates, both electronic and steric effects should lead to the same direction of addition.…”

Section: Resultsmentioning

confidence: 99%

Further Observations on the Formation of Naphthalenes by Double Insertion of Acetylenes into Benzyne−Nickel(0) Complexes

Bennett

Wenger

1996

Organometallics

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The reactions of acetylenes with benzyne−nickel(0) complexes Ni((1,2-η)-4,5-X2C6H2)L2 (X = H, L2 = 2PEt3 (1), dcpe (2); X = F, L2 = 2PEt3 (3), dcpe (4)) to give substituted naphthalenes have been investigated further in an effort to understand the factors that control the successive insertions. Complex 1 reacts with a mixture of tert-butylacetylene and 3-hexyne in a 1:3 molar ratio to give approximately equal amounts of 1,2-diethyl-3-tert-butylnaphthalene (11), the exclusive product of cocyclization, and 1,2,3,4-tetraethylnaphthalene (10), which results from double insertion of 3-hexyne. Double insertion of 1,7-octadiyne into the benzyne−nickel bond of 1 occurs exclusively in an intramolecular fashion to give 1,2,3,4-tetrahydroanthracene (14) in 48% isolated yield. These observations are consistent with the following postulates: (1) the first insertion occurs under steric control and forms a nickelaindene in which the substituted carbon atom is bound to nickel; (2) the second insertion occurs in the nickel−vinyl bond of this species, not the nickel−aryl bond. The second insertion is also under steric control, but the regiospecificities for tert-butylacetylene and 1,7-octadiyne are opposite. Addition of PEt3 or PPh3 suppresses (though not completely) the catalytic cyclotrimerization of methyl propiolate in the presence of 3 in favor of stoichiometric formation of a mixture of dimethyl 6,7-difluoronaphthalenedicarboxylates, the ratio of the 1,3- and 2,3-isomers, 8 and 9, being 1:3 (PEt3) and 1:4 (PPh3). For tert-butyl propiolate in the presence of PPh3, the ratio of 1,3- to 2,3-isomer changes to 1.6:1. These observations support the idea that for acetylenic esters both steric and electronic factors influence the second insertion. The isolated nickelaindene Ni{C6H4C(CO2Me)C(CO2Me)}(dcpe) (18) reacts with methyl propiolate, probably under electronic control, to give trimethyl 1,2,3-naphthalenetricarboxylate as the only product of cocyclization.

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Section: Resultsmentioning

confidence: 99%

Further Observations on the Formation of Naphthalenes by Double Insertion of Acetylenes into Benzyne−Nickel(0) Complexes

Bennett

Wenger

1996

Organometallics

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“…In this connection it should be noted that the use of acetonitrile as a solvent in the reactions of labeled potassium cyanide is strongly limited by the fact that under such conditions exchange occurs with nitrile function of the solvent, resulting in labeled acetonitrile (eq 19).77 Nucleophilic substitution at sulfur is a common reaction of organosulfur compounds and has been extensively studied for dicoordinate, tricoordinate, and tetracoordinate sulfur.39,81-92 A few examples are given by eq 9 and 21-23. [81][82][83][84][85][86][87][88][89][90][91][92] (PhS)4C + BuLi -BuSPh + (PhS)3CLi (21) a 1) n-BuLi 2) H20 n-BuSCH2CH=CH2 n-BuSCH=CHCH3 ( 22) XR' SZ R'i 23)…”

Section: Nucleophilesmentioning

confidence: 99%

X-philic reactions

Зефиров¹,

Makhon'kov²

1982

Chem. Rev.

197

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“…[17] The zwitterion A thus formed undergoes proton transfer, presumably pyridine-assisted (this explains the favorable effect of the excess pyridine), via the intermediate None of the anticipated adducts were detected when the reaction was conducted in the presence of cyclohexene (20-25°C, 18 h) or ethoxyethene (20-25°C, 26 h) as carbene trappers, probably due to the nucleophilic character and extensive delocalization (hence low reactivity) of the postulated carbene B.…”

Section: Resultsmentioning

confidence: 99%

Reaction of Pyridine with Phenylcyanoacetylene: A New Route to Functionalized Polyconjugated 1,4‐Dihydropyridine Systems

et al. 2006

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Pyridine reacts with phenylcyanoacetylene under mild conditions (20–25 °C, no catalyst) to unexpectedly give the 2:3 adduct — a C,N‐functionalized polyconjugated 1,4‐dihydropyridine system — containing two 1,4‐dihydropyridine cycles and four vinylene units formed by three molecules of phenylcyanoacetylene (the yield is up to 46 %). Other products are higher oligomers of phenylcyanoacetylene terminated by 1,4‐dihydropyridine cycles (approx. 30 % yield). Assembly of the 2:3 adduct proceeds regio‐ and stereoselectively — only one of the possible isomers is formed. The oligomers show paramagnetic and electroconductive properties. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Nucleophalic attacks on acetylenes

Cited by 40 publications

References 0 publications

Further Observations on the Formation of Naphthalenes by Double Insertion of Acetylenes into Benzyne−Nickel(0) Complexes

Further Observations on the Formation of Naphthalenes by Double Insertion of Acetylenes into Benzyne−Nickel(0) Complexes

X-philic reactions

Reaction of Pyridine with Phenylcyanoacetylene: A New Route to Functionalized Polyconjugated 1,4‐Dihydropyridine Systems

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