Dr. Biswas and colleagues have introduced a novel approach for synthesizing imidazo[1,2-a]pyridines and imidazo[2,1-b]thiazoles through the Brønsted acid-catalyzed regioselective ring opening of 2H-azirines. This method demonstrates the capability to yield the desired products in moderate to good yields. In my view, once the following issues are addressed and rectified, this article would be suitable for publication in OBC.

1. "N-heterocyclic": "N" should be italicized.
2. "imidazo[1,2-a]pyridine": "a" should be italicized.
3. "In situ cyclization of the products resulted in the formation of imidazo[1,2-a]pyridine and imidazo[2,1-b]thiazoles derivatives." (Changed "to" to "in")
4. "reaction condition" should be changed to "reaction conditions."
5. Table 1 should be revised to demonstrate the variation more clearly. The current presentation style is unacceptable and difficult to understand.
6. The authors presented only results of yields, lacking scientific discussion in the context of both Tables 2 and 3. Therefore, the results and discussion should be rewritten.
7. "3i and 3j in moderate yields" should be corrected to "4i and 4j in moderate yields."
8. "benzo[d]thiazole-2(3H)-thione provided 3k and 3l in good yields respectively," should correct the compound labels.
9. Explanation is needed when comparing yields of product outcomes to understand why the synthesis of imidazo[2,1-b]thiazole provided lower yields than the synthesis of imidazo[1,2-a]pyridine derivatives.
10. "an important bio-active molecule, anti-tumor agent 6 (Scheme 4b)": Remove the hyphen in "Bio-active."
11. The proposed reaction mechanism (Scheme 5) needs revision because the reactions were conducted under acidic conditions. Therefore, acids will facilitate all steps for the formation of intermediates D and E.

The updated version of the manuscript addresses all comments and concerns. Consequently, I believe it is ready for publication in OBC