I₂-Mediated Iodobenzannulation of Yne-Allenones toward 1-Naphthols and Their Synthetic Application

Abstract

A new I 2 -mediated iodobenzannulation of yne-allenones has been established, enabling breaking/rearranging of CC bonds to selectively access 4-iodonaphthalen-1-ols with generally good yields. The resulting 4iodonaphthalen-1-ols could serve as a new and reliable coupling reagent, which further reacted with H 2 O under the oxygen conditions to generate unexpected 1,2-carbonyls with good yields through Pd-catalyzed deiodinated carbonylation, whereas employment of benzene-1,2-diamine as the nucleophile rendered 3-(quinoxalin-2-yl)naphthalen-1-ols through Pd-catalyzed [4 + 2] heterocyclization. On the basis of the controlled experiments, the mechanism for forming 1,2-carbonyls was proposed, including an oxidative addition, 1,3-palladium migration, reductive elimination, and oxidative dehydrogenation sequence.

Synthesis of 3,4‐Dihydrobenzo[f]phthalazines via Iodine/tert‐Butyl Hydroperoxide‐Mediated Annulation Cascade of Yne‐Allenones

“…Subsequent ring‐opening of B in the presence of I 2 gives iodomethyl substituted 1‐naphthol intermediate 5 , which converts into the final products 4 through intramolecular nucleophilic substitution. The observation of ring‐opening of cyclobutene ring is different from our previous reports . The reason may be attributed to the strong nucleophilicity and steric hindrance of sulfonyl hydrazides, which could suppress I 2 to activate the double carbon−carbon from cyclobutene ring of intermediate A and to inhibit the formation of iodide ion between A and I 2 .…”

“…The very inferior result was observed when I 2 was replaced by Br 2 (entry 11). A relatively lower conversion was observed with the reaction temperature being at 40, or 60°C (entries [12][13]. Next, our endeavors aimed at improving the formation of 4 a were contributed by changing the reaction media.…”

“…The observation of ringopening of cyclobutene ring is different from our previous reports. [12] The reason may be attributed to the strong nucleophilicity and steric hindrance of sulfonyl hydrazides, which could suppress I 2 to activate the double carbonÀ carbon from cyclobutene ring of intermediate A and to inhibit the formation of iodide ion between A and I 2 . With Et 3 N, intramolecular nucleophilic substitution is more favourable.…”

Fe(III)-Catalyzed Bicyclization of Yne-Allenones With Indoles for the Atom-Economic Synthesis of 3-Indolyl Cyclobutarenes

“…X-Ray crystallographic analysis was performed with a SMART CCD and a P4 diffractometer (the copies of NMR see Supplementary Material). All yne-allenones 1 are known compounds and their preparation followed the previously reported procedures (Wei et al, 2009; Liu et al, 2017a; Li et al, 2018b).…”

“…To continue our efforts in this project (Liu et al, 2017a; Wang J.-Y. et al, 2017; Li et al, 2018a,b; Sha et al, 2018b; Wang et al, 2018), we attempted to employ indoles 2 to be subjected with the reaction of yne-allenones 3 under our previous conditions (Li et al, 2018a) to assemble naphtho[1,2- a ]carbazol-5-ols 4 (Scheme 1d), owing to indoles with C2 and C3 reactive sites could acted as C 2 synthons for the synthesis of fused indoles (Haibach et al, 2011; Li et al, 2015; Liu et al, 2016; Ozaki et al, 2017). Unexpectedly, a double [2 + 2] cycloaddition relay did not occur.…”