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Since its discovery in the late 1960s, the Morita–Baylis–Hillman (MBH) reaction has remained a powerful carbon–carbon σ-bond-forming transformation, producing small polyfunctionalized molecules. While commonly catalyzed by Lewis basic organic molecules such as tertiary amines and phosphines, several advances in functional catalysts and reaction conditions have been made in order to improve the reaction rate, substrate scope, and enantioselectivity. The goal of this Review is to give an updated summary of the main improvements made in catalytic systems for the MBH reaction over the past decade until nowadays. We hope this account will instigate further investigations in order to circumvent the remaining challenges of this fascinating transformation.

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Background: The most important cause of dementia affecting elderly people is the Alzheimer’s disease (AD). Patients affected by this progressive and neurodegenerative disease have severe memory and cognitive function impairments. Some medicines used for treating this disease in the early stages are based on inhibition of acetylcholinesterase. Population aging should contribute to increase the cases of patients suffering from Alzheimer's disease, thus requiring the development of new therapeutic entities for the treatment of this disease. Methods: The objective of this work is to identify new substances that have spatial structural similarity with donepezil, an efficient commercial drug used for the treatment of Alzheimer's disease, and to evaluate the capacity of inhibition of these new substances against the enzyme acetylcholinesterase. Results: Based on a previous results of our group, we prepared a set of 11 spirocyclohexadienones with different substitutions patterns in three steps and overall yield of up to 59%. These compounds were evaluated in vitro against acetylcholinesterase. We found that eight of them are able to inhibit the acetylcholinesterase activity, with IC50 values ranging from 0.12 to 12.67 µM. Molecular docking study indicated that the spirocyclohexadienone, 9e (IC50 = 0.12 µM), a mixedtype AChE inhibitor, showed a good interaction at active site of the enzyme, including the cationic (CAS) and the peripheral site (PAS). Conclusion: We described the first study aimed at investigating the biological properties of spirocyclohexadienones as acetylcholinesterase inhibitors. Thus, we have identified an inhibitor, which provided valuable insights for further studies aimed at the discovery of more potent acetylcholinesterase inhibitors.