The Baylis-Hillman reaction is a successful, useful, and atom-economical carbon-carbon bond forming reaction, which has grown from an obscure level to the level of high synthetic popularity due to its operational simplicity and also due to the enormous applications of the Baylis-Hillman adducts in organic synthesis. In this tutorial review, we briefly describe the way this reaction has grown to its present heights and the opportunities, attractions, and challenges the reaction offers with respect to its asymmetric and intramolecular versions, and mechanistic aspects.
This review provides a unique and comprehensive overview of sodium sulfinates for synthesizing many valuable sulfur-containing compounds, such as thiosulfonates, sulfonamides, sulfides, sulfones, allyl sulfones, vinyl sulfones and β-keto sulfones.
Non‐oxidative, regioselective, and convergent access to densely functionalized oxazoles is realized in a functional‐group tolerant manner using alkynyl thioethers. Sulfur‐terminated alkynes provide access to reactivity previously requiring strong donor‐substituted alkynes such as ynamides. Sulfur does not act in an analogous donor fashion in this gold‐catalyzed reaction, thus leading to complementary regioselective outcomes and addressing the limitations of using ynamides.
Oxazolesa re important motifs within bioactive and functional materials.C omplex, fully substituteda nd functionalised 4-aminooxazoles are accessed by an efficienti ntermolecular reactionb etween an ynamide and an N-acylpyridinium N-aminide in the presence of ag old catalyst. Thef ormal [3+ +2] dipolar cycloaddition employs an ucleophilic nitrenoid approach to access the 1,3-N,O-dipole character in ac ontrollable fashion.T he selectivity for ac ycloaddition pathwayp rovides as tark contrast against the indiscriminate reactivity of electrophilic acyl nitrenes.P rotocolsf or the formation of acylfunctionalised aminides are reported from accessible precursors including carboxylic estersa nd acids.T he function of these aminides in the oxazole-forming reaction has been exploreda nd it is shown that substantial elaboration is accommodated despite proximity to the reactivec entre.A saresult functional oxazole-based motifs,s uch as chiral oxazoles with biologically pertinent substitution patterns,a re readily accessible.T he use of ynamide types that are unexplored or little used in gold catalysis has been evaluated. Unusual all-heteroatom substitution patterns around the oxazole are shown to be accessible using thio-ynamides.T he studys hows that ac lose stoichiometry of reactantsi ss uitable alongsider elatively low loadings of the bench-stable precatalysts in practicallys traightforward multi-mmol scale reactions.T he efficiency and flexibility of this regioselective intermolecular preparation is demonstrated in the ready synthesis of oxazoles with substantial structural and functional group variation.
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