Correction: Wu et al. Synthesis of Spirooxindole-O-Naphthoquinone-Tetrazolo[1,5-a]Pyrimidine Hybrids as Potential Anticancer Agents. Molecules 2018, 23, 2330

In the original publication [1], we found that there was a mistake in the structures of compound 4. As the figure below shows, the structure of compound 4 should be “1,6-dihydro” instead of “4,6-dihydro” [2,3]. The authors did not notice the mistake before the article was published, and they would like to thank Dr. Essam M. Eliwa who pointed it out. A correction is needed for all data describing the structure of compound 4. The corrections of the figures, schemes, and data affected appear below.

Graphical Abstract

Error in Results and Discussion

In the original publication [1], there was a mistake in both the first and third paragraphs of the Results and Discussion section. The correct text appears below.

To achieve the optimum conditions, the synthesis of 1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4a) was used as a model reaction under a variety of different conditions.

A suggested pathway for the formation of the hybrid is shown in Scheme 2. Keto form of 2-hydroxy-1,4-naphthoquinone undergoes Knoevenagel condensation with isatin to form olefin. The olefin can react with 5-aminotetrazole by carbonyl-amine condensation to produce the secondary ketamine, which further undergoes intramolecular cyclization via aza-Michael addition to generate C3-spirooxindole product.

Error in Schemes and Figure

The corrected Scheme 1 appears below:

The corrected Figure 2 appears below:

The corrected Scheme 2 appears below:

Error in Materials and Methods

In the original publication [1], there was a mistake in the compound names described in Section 3.2. of the Materials and Methods. The correct compound names appear below.

• 1,6-Dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4a)
• 5′-Bromo-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4b)
• 5′-Chloro-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4c)
• 6′-Bromo-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4d)
• 1′-Methyl-7′-fluoro-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4e)
• 7′-Chloro-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4f)
• 5′-Fluoro-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4g)
• 7′-Bromo-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4h)
• 1′-Phenyl-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4i)
• 5′-Methyl-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4j)
• 6′-Chloro-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4k)
• 6′-Methoxyl-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4l)
• 5′-Trifluoromethoxyl-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4m)
• 7′-Trifluoromethyl-1,6-dihydro–spiro[benzo[h]tetrazolo[5,1-b]-quinazoline-6,3′-indoline]-2′,7,8-trione (4n)

In addition, the original text was also corrected to address minor text formatting issues.

Error in Supplementary Materials

The structures of the above-mentioned compounds 4a–4n were corrected in the ¹H-NMR, ¹³C-NMR and HRMS data in the Supplementary Materials.

The authors state that the scientific conclusions are unaffected. The original publication has also been updated.