Intramolecular Anionic Friedel-Crafts Equivalents. A General Regiospecific Route to Substituted and Naturally Occurring Xanthen-9-ones

Familoni, Oluwole B.; Ionica, I.; Bower, Justin; Snieckus, Victor

doi:10.1055/s-1997-1533

Cited by 60 publications

(36 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Remarkable improvements have been achieved in the synthesis of 1,2-dioxygenated xanthones by application of a direct metalation on diphenyl ether intermediates (Scheme 2, d)) using lithium di-isopropylamide (LDA) [66,67], a method similar to that developed for the synthesis of natural xanthones cervinomycin A1 and A2 (see Table 2) [68]. An attempt to obtain 1,2-dihydroxyxanthone (16) by traditional Friedel-Crafts acylation or Ullmann reaction resulted in an isomeric mixture with very low yields of compound (16) [69].…”

Section: Modifications To the Classical Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis of Xanthones: An Overview

Sousa¹,

Pinto

2005

CMC

125

View full text Add to dashboard Cite

Among the known synthetic routes to obtain xanthones, the Grover, Shah, and Shah reaction, the cyclodehydration of 2, 2'-dihydroxybenzophenones and electrophilic cycloacylation of 2-aryloxybenzoic acids are the most popular methods. Due to important biological applications of xanthones, some synthetic strategies leading to more complex derivatives have been widely explored in the past years. Thus, the purpose of this review is to report some recent improvements of the classical synthetic methods as well as of some non-classical methods to obtain simple oxygenated xanthones. The strategies for introduction of substituents into the xanthonic nucleus are also summarized. Furthermore, different approaches used to synthesize complex structures, with an emphasis on the total synthesis of bioactive natural products, accomplished in the last twenty years, are also discussed. Besides the synthesis of xanthones, the reactivity of the xanthonic nucleus and its role as a key intermediate for the synthesis of other important classes of compounds are also highlighted.

show abstract

Section: Modifications To the Classical Methodsmentioning

confidence: 99%

“…However, 1-hydroxyxanthone (63), due to the hydrogen bonding between the hydroxyl group on C1 and the carbonyl at C9, failed to react with 1,1-diphenylprop-2-yn-1-ol in the presence of PPTS to give the pyranoxanthone (66). To circumvent this problem, a synthetic strategy was devised (Scheme 18).…”

Section: Pyranoxanthones and Furanoxanthonesmentioning

confidence: 99%

Synthesis of Xanthones: An Overview

Sousa¹,

Pinto

2005

CMC

125

View full text Add to dashboard Cite

show abstract

“…[91] The presence of a heteroatom in a biaryl framework (177) offers further opportunities for CIPE-induced processes. Thus, thioxanthones 178 a, [100] xanthones 178 b, [101] dibenzophosphorinones 178 c, [102] and acridones 178 d [103] are obtained by simple LDA-mediated reactions of orthounprotected Ar-X-Ar systems 177, which themselves are easily prepared by DoMUllmann, and Buchwald-Hartwig coupling protocols (Scheme 38). Under very similar conditions, two of the Ar-X-Ar series underwent a one-pot anionic remote Fries and amide DreM sequence (177!…”

Section: Scheme 29 Synthesis Of Imelutein (135)mentioning

confidence: 99%

“…Thus, exposure of 181 (which is readily available by the DoM-Ullmann-coupling tactic) to standard LDA conditions afforded 182, which was readily transformed into the natural product 183 (Scheme 39). [101] In the diarylamines series 184, besides the normal DreM (path a), a tolyl deprotonation (path b) is also possible (Scheme 40).…”

Section: Scheme 29 Synthesis Of Imelutein (135)mentioning

confidence: 99%

See 1 more Smart Citation

Beyond Thermodynamic Acidity: A Perspective on the Complex‐Induced Proximity Effect (CIPE) in Deprotonation Reactions

et al. 2004

Self Cite

View full text Add to dashboard Cite

The concept of the complex-induced proximity effect (CIPE) in deprotonations is helpful in elucidating the mechanisms involved in carbanion chemistry and in planning organic syntheses. In this Review, the consequences of complexation of organolithium bases to functional groups of the substrates before the proton-transfer step are discussed. Experimental data from kinetic measurements and isotope-labeling experiments as well as the results of calculations in many cases point to a prelithiation complex as a reaction intermediate. Some examples from natural products synthesis illustrate how this concept can be used to obtain intermediates in a regio- or stereoselective manner. Of particular interest is the functionalization of positions that are remote from the coordination group.

show abstract