Cyclizations of Alkynes: Revisiting Baldwin’s Rules for Ring Closure

Gilmore, Kerry; Alabugin, Igor V.

doi:10.1021/cr200164y

Cited by 457 publications

(231 citation statements)

References 373 publications

(318 reference statements)

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“…At first glance, this distance in the starting compounds 2b could be responsible for the unsuccessful results for the cyclizations with C 2 and C 3 dinucleophiles, depending on whether it matched the distance between the reacting sides of the reagent. Of course, this will depend on the reaction type and mechanism (see, for example, Alabugin's discussion of the Baldwin rules [39] While analyzing the crystal data in order to estimate the geometric "fitness" for the cyclization reaction to occur, one should keep in mind that the solid-state conformation is not necessary sustained in solution. The examples are given in the next section.…”

Section: X-ray Studiesmentioning

confidence: 99%

Piperazine-Based N4-Type 16-Membered Macroheterocycles and Their Nickel(II) Complexes

Вацадзе¹,

Krut’ko²,

Blake³

et al. 2017

MHC

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Square-planar diamagnetic nickel(II) complexes S. Z. Vatsadze et al. конформация сохраняется и в растворе, однако макроцикл оказался конформационно гибким -он подверга-ется вырожденной интерконверсии с активационным барьером 41.9±0.8 кДж/моль.Ключевые слова: 16-Членные макрогетероциклы, диамагнитные комплексы никеля(II), позитронно-эмиссионная томография, рентгеновская дифракция, ЯМР спектроскопия, конформационный анализ. one down), even for the four-coordinate complexes with no additional axial donor ligand(s). We envisaged that such a conformation might, in the long term, allow for asymmetric synthetic applications for metal-ligand multiply-bonded complexes containing such ligands. Finally, we noted that the coordination chemistry of piperazines [10,11] and their open-chain [8,[12][13][14][15][16] and macrocyclic [17][18][19][20][21][22][23] derivatives has only been developed for late transition metals.The coordination and supramolecular, as well as synthetic, chemistry of piperazine-based molecules is a currently emerging area. This activity is defined, first of all, by the conformational features of the piperazine ring. For example, in a recent paper Stucchi et al. reported the application of piperazine-based peptidomimetics.[24] Although Thirunarayanan et al. reported the complexation properties of piperazinophanes, [25] they did not adequately address the conformational behavior of the ring. The other direction of the application of piperazine-based ligands is the use of titanium complexes designed for the ring-opening polymerization of rac-lactide.[26] Piperazine-based macrocycles are known to form supramolecular tubular structures [27] and promising receptor-mimic phanes.[28]In the present work we have synthesized and studied the crystal and solution structures of two Cu(II) and four Ni(II) complexes with N 4 -type ligands (Figure 2).For 1a and 1b it has been shown that anilinic protons could be easily changed for SiMe 3 groups by the action of TMSCl/DABCO (trimethylsilyl chloride / 1,4-diazabicyclo-[2.2.2]octane).[9] The already-mentioned interesting feature of the ligands 1a and 1b in their Ni, Cu, Pd and Ti complexes studied so far, [8,9] is the non-planar, pseudo-C 2 symmetric (transoid) conformation that they adopt.Complexes 5a and 5b were included in this study because they contain the imine nitrogen that favors strong Ni-N bonding due to back-donation from Ni to the π* N=C orbital. Another feature of cyclic diimine ligands 4a and 4b is the rigid xylylidene bridge between imine nitrogens, which creates an additional reason for the cisoid conformation. This conformation is of particular interest for catalysis due to one

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Section: X-ray Studiesmentioning

confidence: 99%

Piperazine-Based N4-Type 16-Membered Macroheterocycles and Their Nickel(II) Complexes

Вацадзе¹,

Krut’ko²,

Blake³

et al. 2017

MHC

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“…This area of organic chemistry has attracted considerable research attention. 5 Earlier we reported 6,7 that the reaction of diarylketoacetylenes with EDA affords acetophenones and 2-substituted imidazoline derivatives. This fragmentation involves total cleavage of the triple bond via three formal reductive stages to form three C-H bonds, whereas other carbon undergoes formal oxidation, i.e.…”

Section: Introductionmentioning

confidence: 99%

Peculiarities of the cascade cleavage of the polarized C≡C-fragment in α-ketoacetylenes on reaction with ethylene diamine

Vasilevsky

Davydova²,

Tomilin³

et al. 2014

Arkivoc

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The reaction of diarylketoacetylenes with ethylenediamine (EDA) leads to arylmethylketones and 2-substituted imidazoline derivatives. This transformation involves complete cleavage of the triple bond via initial intermolecular Michael-addition with subsequent intramolecular Michaeladdition. Final fragmentation can be presented as a retro-Mannich reaction, accompanied by three formal reductive stages (formation of three C-H bonds), while the other carbon undergoes a formal oxidation, in which three C-N bonds (C-N and C=N) are formed.

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“…In this article the authors consider an important aspect of the influence of magnetic field on Baldwin's rule [1][2][3][4][5][6][7][8][9][10][11].…”

Section: Introduction mentioning

confidence: 99%

“…The authors propose to extend the rule Baldwin not only for sp 3 -, sp 2 -and sp-orbits, but and for d 1 -d 10 and f 1 -f 14 elements of I-VIII of the Periodic Table. In the future, work will continue to use the modified rules Baldwin to form a (hetero) cycles with triple, double and single bonds, including for hetero atoms I-VIII of the Periodic Table. This will expand the scope of use of the modified rules Baldwin important in the synthesis of biologically active substances.…”

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confidence: 99%

The New Approach of Expansion Baldwin-Aibassov’s Rules for Ring-Closing Reaction for d- and f-elements Periodic Table of Elements

Yerkin¹,

Valentina²,

Tatyana³

et al. 2017

JCCE

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Cyclizations of Alkynes: Revisiting Baldwin’s Rules for Ring Closure

Cited by 457 publications

References 373 publications

Piperazine-Based N4-Type 16-Membered Macroheterocycles and Their Nickel(II) Complexes

Piperazine-Based N4-Type 16-Membered Macroheterocycles and Their Nickel(II) Complexes

Peculiarities of the cascade cleavage of the polarized C≡C-fragment in α-ketoacetylenes on reaction with ethylene diamine

The New Approach of Expansion Baldwin-Aibassov’s Rules for Ring-Closing Reaction for d- and f-elements Periodic Table of Elements

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