Zincate-Mediated Arylation Reactions of Acridine: Pre- and Postarylation Structural Insights

This study explores the synthetic utility of homo(aryl) lithum zincate reagents [LiZnPh3] (2) and [Li2ZnPh4] (3), made by cocomplexation of variable amounts of their monometallic components LiPh and ZnPh2 (1), as chemoselective nucleophilic arylating reagents. Lithium zincates 2 and 3 were both char...

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Main Author: Cadenbach, Spyros Thomas
Format: Artículos
Language:eng
Published: 2016
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spelling oai:localhost:28000-30112017-04-17T17:25:25Z Zincate-Mediated Arylation Reactions of Acridine: Pre- and Postarylation Structural Insights Cadenbach, Spyros Thomas ZINCATE-MEDIATED REACTIONS OF ACRIDINE POSTARYLATION STRUCTURAL INSIGHTS This study explores the synthetic utility of homo(aryl) lithum zincate reagents [LiZnPh3] (2) and [Li2ZnPh4] (3), made by cocomplexation of variable amounts of their monometallic components LiPh and ZnPh2 (1), as chemoselective nucleophilic arylating reagents. Lithium zincates 2 and 3 were both characterized by multinuclear (1H, 13C, and 7Li) NMR spectroscopy, and in the case of 2, a classical reagent in heterobimetallic chemistry, the molecular structure of its OnBu2 solvate [LiZnPh3(OnBu2)2] 2?2OBu2 has been established by X-ray crystallography. Using the synthetically relevant N-heterocyclic molecule acridine (acr, NC13H9), a new zincate-mediated arylating approach is demonstrated which allows the chemoselective arylation of acr at its C9 position, affording 9,10-dihydro-9-phenylacridine (4) in 95% yield using microwave irradiation (125 ?C, 20 min). These conditions are in contrast with previous transition-metal-catalyzed methodologies using ZnPh2 as an arylating reagent, which require significantly longer reaction times (130 ?C, 20 h). Oxidation of 4 with DDQ furnished 9-phenylacridine (5) in a 71% yield. New insights into the constitution of the intermediate organometallic species involved in these reactions prior to the hydrolysis step have been gained by trapping homometallic [(THF)3Li(NC13H9-Ph)] (6). Interestingly the reaction of acr with 3 equiv of PhLi/TMEDA led to the isolation of a different product, namely the novel paramagnetic [(THF)(TMEDA)Li{NC13H8-Ph}??] (7), which contains a radical anion of 9-phenylacridine. The structure of the donor?acceptor complex [(acr)ZnPh2] (8) has also been included as a result of the reaction of 1 with acr. Escuela Polit?cnica Nacional http://pubs.acs.org/doi/abs/10.1021/om501251q 2016-11-09T16:29:23Z 2016-11-09T16:29:23Z 2015 article Hern?n - G?mez, Alberto. et al.(2015). Zincate-Mediated Arylation Reactions of Acridine: Pre- and Postarylation Structural Insights. Organometallics. Vol.34, N?11. pp.2614-2623 0276-7333 eng https://www.ncbi.nlm.nih.gov/pubmed/26331635 restrictedAccess pp.2614-2623
institution SENESCYT
collection Repositorio SENESCYT
biblioteca Biblioteca Senescyt
language eng
format Artículos
topic ZINCATE-MEDIATED
REACTIONS OF ACRIDINE
POSTARYLATION
STRUCTURAL INSIGHTS
spellingShingle ZINCATE-MEDIATED
REACTIONS OF ACRIDINE
POSTARYLATION
STRUCTURAL INSIGHTS
Cadenbach, Spyros Thomas
Zincate-Mediated Arylation Reactions of Acridine: Pre- and Postarylation Structural Insights
description This study explores the synthetic utility of homo(aryl) lithum zincate reagents [LiZnPh3] (2) and [Li2ZnPh4] (3), made by cocomplexation of variable amounts of their monometallic components LiPh and ZnPh2 (1), as chemoselective nucleophilic arylating reagents. Lithium zincates 2 and 3 were both characterized by multinuclear (1H, 13C, and 7Li) NMR spectroscopy, and in the case of 2, a classical reagent in heterobimetallic chemistry, the molecular structure of its OnBu2 solvate [LiZnPh3(OnBu2)2] 2?2OBu2 has been established by X-ray crystallography. Using the synthetically relevant N-heterocyclic molecule acridine (acr, NC13H9), a new zincate-mediated arylating approach is demonstrated which allows the chemoselective arylation of acr at its C9 position, affording 9,10-dihydro-9-phenylacridine (4) in 95% yield using microwave irradiation (125 ?C, 20 min). These conditions are in contrast with previous transition-metal-catalyzed methodologies using ZnPh2 as an arylating reagent, which require significantly longer reaction times (130 ?C, 20 h). Oxidation of 4 with DDQ furnished 9-phenylacridine (5) in a 71% yield. New insights into the constitution of the intermediate organometallic species involved in these reactions prior to the hydrolysis step have been gained by trapping homometallic [(THF)3Li(NC13H9-Ph)] (6). Interestingly the reaction of acr with 3 equiv of PhLi/TMEDA led to the isolation of a different product, namely the novel paramagnetic [(THF)(TMEDA)Li{NC13H8-Ph}??] (7), which contains a radical anion of 9-phenylacridine. The structure of the donor?acceptor complex [(acr)ZnPh2] (8) has also been included as a result of the reaction of 1 with acr.
author Cadenbach, Spyros Thomas
author_facet Cadenbach, Spyros Thomas
author_sort Cadenbach, Spyros Thomas
title Zincate-Mediated Arylation Reactions of Acridine: Pre- and Postarylation Structural Insights
title_short Zincate-Mediated Arylation Reactions of Acridine: Pre- and Postarylation Structural Insights
title_full Zincate-Mediated Arylation Reactions of Acridine: Pre- and Postarylation Structural Insights
title_fullStr Zincate-Mediated Arylation Reactions of Acridine: Pre- and Postarylation Structural Insights
title_full_unstemmed Zincate-Mediated Arylation Reactions of Acridine: Pre- and Postarylation Structural Insights
title_sort zincate-mediated arylation reactions of acridine: pre- and postarylation structural insights
publishDate 2016
_version_ 1634995100608102400
score 11,871979