N-Methylmorpholine and Urotropine as Useful Base Catalysts in Baylis-Hillman Reaction

Abstract

N-Methylmorpholine and urotropine, inexpensive mild bases, have effectively been utilized as catalysts in Baylis-Hillman reaction to result in good to excellent yields (57-99%) of the products.

Recent Contributions from the Baylis−Hillman Reaction to Organic Chemistry

“…Later on, Krishna and co-workers (Path A, Scheme ) and Vasconcellos and co-workers (Path B, Scheme ) about the same time reported application of urotropine (HMTA) for performing the Baylis−Hillman reaction between activated alkenes and aldehydes. It should be mentioned here that urotropine was used for the first time as a catalyst for performing Baylis−Hillman reaction a few years ago by Tang and co-workers (only one example was reported).…”

“…Subsequently N -methylmorpholine (NMM) was used as a catalyst for the Baylis−Hillman coupling of various activated alkenes with electrophiles by Krishna and co-workers . Representative examples are given in Scheme .…”

Nucleophilic reactivities of tertiary alkylamines

“…Tertiary alkylamines are generally used as Brønsted bases in organic synthesis 1–2. On the other hand, many reactions are known, where tertiary amines act as nucleophilic catalysts 3–32. 1,4‐Diazabicyclo[2.2.2]octane (DABCO, 1e ) and quinuclidine ( 1f ), for example, are common catalysts in Baylis–Hillman reactions7 and in cyclopropanations of Michael acceptors 8 .…”

“…1,4‐Diazabicyclo[2.2.2]octane (DABCO, 1e ) and quinuclidine ( 1f ), for example, are common catalysts in Baylis–Hillman reactions7 and in cyclopropanations of Michael acceptors 8 . N ‐Methylpiperidine ( 1c ) and N ‐methylmorpholine ( 1d ) have been reported to function as nucleophilic catalysts in Baylis–Hillman reactions,9, 10 and N ‐methylmorpholine ( 1d ) served as a catalyst for the aziridination of α , β ‐unsaturated carbonyl compounds 11–13. Though acylations are commonly catalyzed by pyridines, in particular 4‐dimethylaminopyridine (DMAP),14–18 triethylamine ( 1a ),19–27 and the cyclic amines 1b 27 and 1c 23 have also been employed as acylation catalysts.…”

Asymmetric Baylis-Hillman Reaction: An Enchanting Expedition

“…9 In fact, the formation of adducts was cleaner and faster rates were accomplished when the Baylis-Hillman reaction was conducted using sulfolane as the solvent. Unlike the previous case where 1,4-dioxane-H 2 O was used as the solvent, this reaction avoids the excess use of ethyl acrylate as hydrolysis is no longer a competing reaction.…”