82819-70-3Relevant articles and documents
Directed ortho-Metalation of O-Aryl N,N-Dialkylcarbamates: Methodology, Anionic ortho-Fries Rearrangement, and Lateral Metalation
Miah, M. A. Jalil,Sibi, Mukund P.,Chattopadhyay,Familoni, Oluwole B.,Snieckus, Victor
, p. 440 - 446 (2017/12/15)
The directed ortho-lithiation reactions of O-aryl N,N-dialkylcarbamates as well as O-1-naphthyl and O-2-naphthyl N,N-dialkylcarbamates with sec-butyllithium/tetramethylethylenediamine (sBuLi/TMEDA) followed by quenching with various electrophiles afford a range of polysubstituted aromatic compounds. If the solutions of the ortho-lithiated carbamates are warmed to room temperature without the addition of external electrophiles, salicylamide and 1- and 2-hydroxynaphthamide derivatives are formed through anionic ortho-Fries rearrangements. The relative stabilities and reactivities of different O-aryl N,N-dialkylcarbamates were investigated. The lateral metalation of 2-tolyl carbamates with lithium diisopropylamide (LDA) provides a route to benzo[b]furan-2(3H)-ones. Previously reported results are used in a comparison of seven O-based directed metalation groups in reactions with several electrophiles. The described methodology is useful for the preparation of 1,2,3-substituted aromatic compounds.
Mise au point. Reaction de metallation ortho dirigee des composes aromatiques. Nouvelles methodologies et applications en synthese organique
Snieckus, Victor
, p. 67 - 78 (2007/10/02)
In recent years, the aromatic directed metalation reaction has developed into a broadly useful protocol for the regiospecific construction of polysubstituted aromatics and has been applied in efficient total syntheses of diverse classes of natural products.In this review, both methodological and total synthesis advences using primarily the tertiary carboxamide and carbamate as metalation directors are presented.First, general aspects such as the nature of the directed metalation group (DMG) (scheme 1), the effect of two meta-related DMGs on the metalation process (scheme 2), the relative directed metalation abilities of different DMGs (scheme 3), and the scope of reaction with various electrophiles (scheme 4) are first discussed.Next, the advantage of the directed metalation tactic for the synthesis of several classes of natural products (anthramycin, scheme 7 ; angular anthracyclinones, scheme 8 ; and cannabifuran, schemes 10 and 11) are conceptualized and briefly described.Further, the significance of silicon functionality in context of directed metalation chemistry is demonstrated by its use for protection of prefferentially reactive aromatic C-H and C-methyl sites (scheme 12), ipso desilylation (scheme 13), generation of o-quinodimethanes (scheme 14), and overcoming normal Friedel-Crafts regioselectivity in carboannelation (schemes 16-18).Aspects of the tertiary carbamate as a ortho metalation director (scheme 19) are delineated : the development of an anionic ortho-Fries rearrangement (scheme 21) ; a new, also anionic, ortho-tolyl carbamate rearrangement leading to benzofuranones (scheme 22) ; its comparison with tertiary amide a methoxymethoxy as a DMG (scheme 23) ; its use for the generation of benzamide benzyne intermediates (scheme 24) ; metalation of O-pyridyl carbamates (scheme 25) and its synthetic ramifications (schemes 26-28) ; and its application in conjunction with amide metalation for the synthesis of the ochratoxin metaolites (scheme 29).Dimetalation of benzamides (scheme 32), phthalamides (scheme 33), p,p- and o,o-aryl dicarbamates (schemes 34 and 35) are supported by reactions with various electrophiles.To conclude, recent work aimed at connecting the aromatic directed metalation strategy to other modern synthetic methods is described.Coupling the directed metalation process with the radical-induced annelation provides new routes to benzofurans (scheme 36) and furopyridines (scheme 37) and is applied to the preparation of a key synthon for the mould metabolite, aflatoxin (scheme 38).Anionic aromatic and heteroaromatic ring annelation processes which depend upon ortho metalated precursors lead to naphthalene (schemes 39-41) and 4-quinolone (scheme 42) derivatives.Aryl boronic acids with ortho-DMGs, synthesized by metalation-boronation and ipso borodesilylation methods, are cross coupled with aryl bromides under palladium (O) catalysis leading to new routes for the preparation of unsymmetrical biaryls (scheme 45).
REACTION OF PHENOL WITH DIETHYLCARBAMOYL CHLORIDE IN THE PRESENCE OF LEWIS ACID
Isakova, A. P.,Naumov, Yu. A.,Nikeryasova, S. V.,Stepanova, A. A.
, p. 1115 - 1119 (2007/10/02)
In the presence of either SnCl4 or AlCl3, phenol reacts with diethylcarbamoyl chloride to give phenyl N,N-diethylcarbamate, which undergoes the Fries rearrangement at 170-180 deg C and is capable of being acylated by diethylcarbamoyl chloride in the para position.
