5-(1H-Indol-3-yl)-1-methyl-3-phenyl-1,6-benzodiazocin-2(1H)-one

Round 1

Reviewer 1 Report

The authors report on the synthesis of an interesting benzodiazocin derivative building on their previously described work. The title compound has not been reported previously and, as such, the paper falls nicely within the scope of molbank. I recommend publication subject to the following changes.

-      Lines 40-41 remove “in equimolar ratio”

-      Can the authors comment on the reaction mechanism?

-      Some additional key 2D-NMR data should be included to support the structural assignment.

-      The authors are encouraged to include coupling constants for all resolved peaks e.g. 7.04-7.11 7.18-7.27, 7.5 and 8.38.

Author Response

Reviewer 1 wrote: “Lines 40-41 remove “in equimolar ratio””

Answer: done as recommended

Reviewer 1 wrote : “Can the authors comment on the reaction mechanism?”

Answer: The reaction mechanism is under study. We propose, that the reaction proceeds via zwitterionic intermediate, adduct of nucleophilic addition of benzimidazole to the electron-deficient acetylene, and the product of its further transformation - carbenic intermediate. The latter undergoes intramolecular nucleophilic addition to the carbonyl group. Further cascade transformations lead to the target product.

Because this manuscript is submitted to the journal as a “Short Note”, according to the authors’ guidelines, the proposed mechanism of the target product formation is not provided.

Reviewer 1 wrote : “Some additional key 2D-NMR data should be included to support the structural assignment.”

Answer: HMBC, HSQC and COSY NMR spectra for supporting the structure have been done and included to the supplementary materials. According to these data, some assignments in the text were corrected. The changes of signals assignments are marked with yellow.

Reviewer 1 wrote : “The authors are encouraged to include coupling constants for all resolved peaks e.g. 7.04-7.11 7.18-7.27, 7.5 and 8.38.”

Answer: To meet the reviewer recommendation and according to additional 2D-NMR data we included coupling constants for indicated resolved peaks: 7.05 (d, ³J_H9,H10 = 7.9 Hz, 1H, H-10), 7.09 (t, ³J_H4’,H5’ = 7.6 Hz, ³J_H5’,H6’ = 7.6 Hz, 1H, H-5’), 7.20 (t, ³J_H5’,H6’ = 7.6 Hz, ³J _H6’,H7’ = 8.0 Hz, 1H, H-6’), 7.23-7.29 (m, 2H, H-8, H-9), 7.49 (d, ³J_H7,H8 = 8.0 Hz, 1H, H-7), 7.51 (d, ³J_H6’,H7’ = 8.0 Hz, 1H, H-7’), and 8.39 (d, ³J_H4’,H5’ = 7.6 Hz, 1H, H-4’) ppm.

Reviewer 2 Report

B. A. Trofimov and his group described a synthesis of 5-(1H-indol-3-yl)-1-methyl-3-phenyl-1,6-benzodiazocin-2(1H)-one. This type of product, benzodiazocinone, was obtained as a by-product during the synthesis of arylaminovinylketones from the corresponding benzimidazoles and acylacetylenes.
The synthetic procedure is fine, and the structural analysis and the spectrum data are also well organized to show the product.  Overall, the manuscript is enough for publication on Molbank as Short Note and I think the paper would be accepted in present format.

Author Response

The reviewer recommended publication of the paper in its present form