Reaction of guanidine with peri-substituted (R-ethynyl)-9,10-anthraquinones bearing electron-donating substituents

Abstract

2 Amino 3 aroyl 7H dibenzo [de,h]quinolin 7 ones were synthesized by the reaction of guanidine with peri (R ethynyl) 9,10 anthraquinones in boiling n butanol.

Divergent Cyclizations of 1-R-Ethynyl-9,10-anthraquinones: Use of Thiourea as a “S2–” Equivalent in an “Anchor-Relay” Addition Mediated by Formal C–H Activation

“…On the other, the observed lack of reactivity of 1-mesitylethynyl-9,10-anthraquinone 1h illustrates the importance of steric factors. The analogous effect has been observed in the reaction of 1-mesitylethynyl-9,10-anthraquinone with urea and guanidine …”

“…The starting 1-R-ethynyl-9,10-anthraquinones 1a – g were prepared via the standard Sonogashira and Castro reactions as described earlier. , Reaction with excess thiourea was carried out in polar solvents in the presence of sodium ethoxide. For substrates 1a,e , this procedure leads to the formation of two heterocyclic products: 2-R-7 H -dibenzo[ de , h ]quinolin-7-ones 2 and 2-R-anthra[2,1- b ]thiophene-6,11-diones 3 .…”

“…Previously, we have shown that the reaction route in peri -R-ethynyl-9,10-anthraquinones is, to a large extent, defined by the nature of nucleophile. For example, the reaction of 1-R-ethynyl-9,10-anthraquinones with hydrazine leads to the formation of heterocycles I and II, with guanidine I, III, and IV, whereas interaction with urea leads to the formation of only I . All products arise from nucleophilic attack at C-9 (the carbonyl), initiating the cascade (Figure ).…”

Alkynes as Synthetic Equivalents of Ketones and Aldehydes: A Hidden Entry into Carbonyl Chemistry

“…Several reaction cascades originate from alternative cyclization modes proceeding via N -6-endo-dig-, N -6-exo-dig- and O -5- exo-dig attacks. The ratio of these products is sensitive to the nature of alkyne substitution, i.e., donor Ar groups favor the formation of 6-exo-dig products [71] whereas the acceptor p -nitrophenyl group directs the reaction towards the heterocyclic amides via the 5-exo-dig step. The 5-exo-product undergoes a subsequent transformation which is formally equivalent to the full cleavage of the triple bond and insertion of a nitrogen atom between the two acetylenic carbons (to be discussed in Section 5).…”

Conformational Flexibility of Fused Tetracenedione Propellers Obtained from One-Pot Reductive Dimerization of Acetylenic Quinones

“…These cascade transformations were found to be quite sensitive to the nature of alkyne substitution, because the triple bond polarization is reflected in the ratio of three cyclization products formed via N-6- endo-dig , N-6- exo-dig , and O-5- exo-dig attacks. Electron-donating Ar groups favor the formation of 6- exo-dig products, whereas the electron-withdrawing p -nitrophenyl directs the reaction toward the heterocyclic amides via the 5- exo-dig step (Scheme ).…”