Intercepted Meyer–Schuster Rearrangements in Organic Synthesis

Abstract

The Meyer-Schuster rearrangement of propargylic alcohols is at ransformation in organic synthesis known for almost ac entury. The products of this reaction-a,b-enones and their a-functionalized units-are highly important functional groups for various synthetic transformations. Two modificationso ft his classical reaction, which involves inter-ceptiono ft he intermediate allenol (or its equivalent) by either electrophiles or nucleophiles, have attracted the attention of synthetic organic chemists. This Focus Review provides ad etailed description of the developmento ft hese two strategies. Intercepted Meyer-Schuster RearrangementsOver the last decade, new variants of the M-S rearrangement of propargylic alcohols 10 (Scheme 3) have been developed to broaden the utility of this classical process in synthetic organic chemistry.T wo of these variants are intercepted (electrophile and nucleophile)M -S rearrangements. These new processes Scheme1.The classicalMeyer-Schusterrearrangement.Scheme2.The Rupe rearrangement.Scheme3.Generalrepresentation of an electrophile-intercepted Meyer-Schuster rearrangement.Scheme4.First reportont he electrophile (halogen)-intercepted Meyer-Schuster rearrangement.Scheme5.Twop ossible mechanistic pathways for the halogen-intercepted Meyer-Schusterr earrangement.Scheme6.Mo-and Au-based cooperative catalysis for the halogen-intercepted Meyer-Schusterr earrangement.Scheme7.Substrate scope of cooperatively Mo-and Au-catalyzed iodo-intercepted Meyer-Schuster rearrangement.Scheme8.HOI-promoted, formaliodo-interceptedM eyer-Schusterr earrangement.Scheme11. Substrate scope for synthesis of a-iodoacrylates.Scheme12. Synthesis of a-iodochalcones from the iodo-intercepted Meyer-Schuster rearrangement of aryl propargylic alcohols.Scheme13. Chloro-intercepted Meyer-Schusterrearrangement by VOCl 3 . Scheme21.Dual Cu-Re-catalyzed CF 3 -intercepted Meyer-Schusterrearrangement.Scheme22. Mechanism for CF 3 -intercepted Meyer-Schusterrearrangement by Cu-Re dual catalysis.Scheme 23. Cu I -catalyzed Z-selective trifluoromethylation during Meyer-Schuster rearrangement.

Recent Developments in the Meyer‐Schuster Rearrangement

“…Two comprehensive reviews have been published to describe the progress of this reaction, [2] with the most recent in 2009 [3] . Some other, more focused, excellent reviews have also been presented, such as one on “intercepted Meyer‐Schuster” [4] . On the other hand gold catalysis, as well as transition metal‐catalyzed reactions of propargylic derivatives, have been much studied during the last decade, and therefore the progress for MSR has also been included in corresponding review articles [5,6]…”

“…[3] Some other, more focused, excellent reviews have also been presented, such as one on "intercepted Meyer-Schuster". [4] On the other hand gold catalysis, as well as transition metal-catalyzed reactions of propargylic derivatives, have been much studied during the last decade, and therefore the progress for MSR has also been included in corresponding review articles. [5,6] Further, a review on cascade reactions includes also a few examples with MSR, [7a] and a very recent review on propargylic alcohols chemistry reports also a number of MSRs.…”

Alcohol Dehydrogenases and N‐Heterocyclic Carbene Gold(I) Catalysts: Design of a Chemoenzymatic Cascade towards Optically Active β,β‐Disubstituted Allylic Alcohols

“…[47][48][49] TheMeyer-Schuster rearrangement consists in the transformation of propargylic (acetylated) alcohols into the corresponding a,b-unsaturated carbonyl compounds,r equiring metal catalysis (Cu, Sc, Hg, Ag, Au,In…), and traditionally performed under harsh reaction conditions (organic solvent, acidic catalysis,h igh temperature.). [42,46,50] This is ah ighly atom economy process occurring via formal 1,3hydroxy shift and tautomerization, that has attracted great attention in the last decades questing for more sustainable solutions.T herefore,akey point of this study is the replacement of conventional organic solvents by aqueous media, making the process compatible with as econd enzymatic reaction, foreseeing the use of NHC gold(I) complexes as asolution for the performance of this selective transformation under milder reaction conditions.…”

Meyer-Schuster Rearrangement—Convenient Synthesis of α,β-Unsaturated α-Iodinated Aldehydes and Ketones

“…Several Meyer-Schuster reactions have been described in two recently published review articles. [4,5] Figure 1 Meyer-Schuster rearrangement of propargyl alcohols.…”