1961-96-2Relevant academic research and scientific papers
Cyclopropenylgold(I) Complexes as Aurated Carbenoids or Quasi-Carbenes
Mulks, Florian F.,Antoni, Patrick W.,Rominger, Frank,Hashmi, A. Stephen K.
, p. 1810 - 1821 (2018)
Highly strained hydrocarbons have always been a research target of high interest. Due to their untypical electronic structure, they show interesting reactivity patterns and can easily be activated by π-coordination to or insertion reactions with metal complexes. Herein we report the synthesis of a range of 3,3-disubstituted cyclopropenylgold(I) complexes. The synthesis of such compounds with a metal, which usually easily activate cyclopropenes is a double-edged sword. We found σ-bound vinylic gold to generally have a strong stabilizing effect in terms of ring strain. The complexes show a strong distortion, preactivating the cyclopropenyls towards the ring-opening mode which thermally generates 1-aurated vinylcarbenes which is reflected by a much faster conversion (Ea of 10 kcal/mol instead of 40 kcal/mol, the reaction proceeds at temperatures as low as ?20 °C instead of 200 °C reported in the literature). In 3-phenyl-cyclopropenyl complexes, these could be trapped intramolecularly to give indenylgold(I) complexes. The properties of these highly strained complexes were investigated, utilizing a range of analytical and experimental procedures and Kohn-Sham density functional theoretic methods. (Figure presented.).
Rh(II)-Catalyzed Alkynylcyclopropanation of Alkenes by Decarbenation of Alkynylcycloheptatrienes
Echavarren, Antonio M.,Mato, Mauro,Montesinos-Magraner, Marc,Sugranyes, Arnau R.
supporting information, p. 10760 - 10769 (2021/07/28)
Alkynylcyclopropanes have found promising applications in both organic synthesis and medicinal chemistry but remain rather underexplored due to the challenges associated with their preparation. We describe a convenient two-step methodology for the alkynyl
The intramolecular reaction of acetophenoneN-tosylhydrazone and vinyl: Br?nsted acid-promoted cationic cyclization toward polysubstituted indenes
Wang, Zhixin,Li, Yang,Chen, Fan,Qian, Peng-Cheng,Cheng, Jiang
, p. 1810 - 1813 (2021/02/27)
In the presence of TsNHNH2, a Br?nsted acid-promoted intramolecular cyclization ofo-(1-arylvinyl) acetophenone derivatives was developed, leading to polysubstituted indenes with complexity and diversity in moderate to excellent yields. In sharp contrast with either the radical or carbene involved cyclization of aldehydicN-tosylhydrazone with vinyl, a cationic cyclization pathway was involved, whereN-tosylhydrazone served as an electrophile and alkylation reagent during this transformation.
Small Gold(I) and Gold(I)–Silver(I) Clusters by C?Si Auration
Pei, Xiao-Li,Pereira, Ana,Smirnova, Ekaterina S.,Echavarren, Antonio M.
supporting information, p. 7309 - 7313 (2020/05/18)
Auration of o-trimethylsilyl arylphosphines leads to the formation of gold and gold–silver clusters with ortho-metalated phosphines displaying 3c–2e Au?C?M bonds (M=Au/Ag). Hexagold clusters [Au6L4](X)2 are obtained by reaction of (L?TMS)AuCl with AgX, whereas reaction with AgX and Ag2O leads to gold–silver clusters [Au4Ag2L4](X)2. Oxo-trigold(I) species [Au3O]+ were identified as the intermediates in the formation of the silver-doped clusters. Other [Au5], [Au4Ag], and [Au12Ag4] clusters were also obtained. Clusters containing PAu?Au?AuP structural motif display good catalytic activity in the activation of alkynes under homogeneous conditions.
Rhenium-Catalyzed Cyclization via 1,2-Iodine and 1,5-Hydrogen Migration for the Synthesis of 2-Iodo-1 H-indenes
Murai, Masahito,Takai, Kazuhiko
supporting information, p. 6756 - 6760 (2019/08/26)
A rhenium complex catalyzed the formation of 2-iodo-1H-indene derivatives through iodine and hydrogen migration of 3-iodopropargyl ethers. The reaction proceeded via generation of 1-iodoalkenylrhenium carbene species by sequential 1,2-iodine and 1,5-hydro
Silver-Catalyzed Allylation of Ketones and Intramolecular Cyclization through Carbene Intermediates from Cyclopropenes under Ambient Conditions
Nakano, Takeo,Endo, Kohei,Ukaji, Yutaka
, p. 713 - 721 (2016/03/09)
Tandem C-C bond formation was achieved through silver-catalyzed ring-opening of cyclopropenes via carbene intermediates. The reaction of cyclopropenes in the presence of a silver catalyst gave indene derivatives under ambient conditions. In contrast, the
Synthesis of 2-bromo-1-aryl-1H-indenes via a Ag(I) promoted domino 2π-electrocyclic ring-opening/4π-electrocyclization reaction of 1,2-diaryl substituted gem-dibromocyclopropanes
Rosocha, Gregory,Batey, Robert A.
, p. 8758 - 8768 (2013/09/23)
2-Bromo-1-aryl substituted indenes can be synthesized from 1,2-diaryl substituted gem-dibromocyclopropanes via a domino reaction sequence. The cascade reaction involves silver(I) promoted ionization and 2π-disrotatory electrocyclic ring-opening, followed by a 4π-conrotatory electrocyclic ring closing reaction of the allylic carbocation intermediate. Reaction conditions utilize silver tetrafluoroborate (AgBF4) in dichloroethane at 65 C. Selectivity effects for the electrocyclization were also studied. The 2-bromoindenes can be further functionalized using cross-coupling reactions, such as the Suzuki-Miyaura protocol. The alkene π-bond of the indenes can also be isomerized to give the thermodynamically more stable 2-bromo-3-aryl-1H-indene isomers using triethylamine in dichloromethane at room temperature.
Flexible and practical synthesis of anthracenes through gold-catalyzed cyclization of o -alkynyldiarylmethanes
Shu, Chao,Chen, Cheng-Bin,Chen, Wei-Xi,Ye, Long-Wu
, p. 5542 - 5545 (2013/11/19)
A concise gold-catalyzed method for the preparation of anthracenes from o-alkynyldiarylmethanes has been developed. Under mild reaction conditions, versatile anthracene derivatives were formed in moderate to good yields. The high flexibility, broad substrate scope, and mild nature of this reaction render it a viable alternative for the synthesis of anthracenes.
Gold for the generation and control of fluxional barbaralyl cations
McGonigal, Paul R.,De Leon, Claudia,Wang, Yahui,Homs, Anna,Solorio-Alvarado, Cesar R.,Echavarren, Antonio M.
supporting information, p. 13093 - 13096 (2013/03/13)
Fluxional molecules which rapidly pass back and forth between a large number of constitutional isomers through low-energy rearrangements have fascinated chemists owing to their role in the study of fundamental theoretical concepts[ 2] and their potential to adapt their chemical structures in response to their environment or to act as prototypical molecular transport systems. They represent a facet of systems chemistry that is relatively unexplored, in which a dynamic structural library can be contained within a single molecule. The 9-barbaralyl cation (1) is a hugely fluxional C9H9 + hydrocarbon that exists as a mixture of 181 400 degenerate forms which interconvert rapidly at temperatures as low as -135 °C-each carbon atom may exchange with every other carbon atom in the structure through a series of pericyclic reactions. Unlike the neutral homologues semibullvalene (2; two degenerate tautomers) and bullvalene (3; 1209600 degenerate tautomers), which are stable compounds under ambient conditions, 1 is highly reactive and undergoes irreversible rearrangement to 1,4-bishomotropylium cation (4) above -125 °C. Functionalized barbaralanes may be suitable candidates for switchable, fluxional molecules. However, the difficulty in handling these compounds coupled with the low-yielding, multistep syntheses and harsh reaction conditions (typically featuring strongly or super acidic media) employed in the generation of 1 and its derivatives have so far limited the extent to which the chemistry of this fascinating dynamic carbon skeleton has been explored.
A Pd(II)-catalyzed ring-expansion reaction of cyclic 2-azidoalcohol derivatives: Synthesis of azaheterocycles
Chiba, Shunsuke,Xu, Yan-Jun,Wang, Yi-Feng
supporting information; experimental part, p. 12886 - 12887 (2009/12/06)
(Chemical Equation Presented) A Pd(II)-catalyzed ring expansion-reaction of cyclic 2-azidoalcohol derivatives was found to proceed via an unprecedented C-C bond cleavage-C-N bond formation sequence, providing substituted azaheterocycles.
