Aldehydes Meyer-Schuster rearrangements

When X=OH, this conversion of acetylenic alcohols to unsaturated aldehydes or ketones is called the Meyer-Schuster rearrangement The propargyl rearrangement can also go the other way that is, 1-haloalkenes, treated with organocopper compounds, give alkynes. ... 

Acid-catalyzed rearrangement of tertiary a-acetylenic (terminal) alcohols, leading to the formation of a,(3-unsaturated ketones rather than the corresponding a,(3-unsaturated aldehydes. Cf. Meyer-Schuster rearrangement. 

It is noteworthy that the indenyl complex RuCl(ri -C9H7)(PPh3)2l4 provides an efficient catalyst precursor for the anti-Markovnikov hydration of terminal alkynes in aqueous media, especially in micellar solutions with either anionic (sodium dode-cylsulfate (SDS)) or cationic (hexadecyltrimethylammonium bromide (CTAB)) surfactants [38]. This system can be applied to the hydration of propargylic alcohols to selectively produce P-hydroxyaldehydes, whereas RuCl(Cp)(PMe3)2 gives a,P-unsat-urated aldehydes (the Meyer Schuster rearrangement products)(Scheme 10.8) [39]. 

Keywords propargyl alcohol, TsOH, Meyer-Schuster rearrangement, cinnamic aldehyde... 

A perusal of the literature discloses that ketones and aldehydes have rarely been reacted with 44. In view of the tendency of ynamines to add water and alkohols, it is obvious that ynamines 56 undergo intramolecular addition of water (Meyer-Schuster rearrangement) quite readily (96). This process is provoked already by silicagel, alumina or it even occurs spontaneously 146). 

Meyer-Schuster rearrangement. Acid catalyzed rearrangement of secondary and tertiary a-acetylenic alcohols to ,(i-unsaturated carbonyl compounds aldehydes when the acetylenic group is terminal, ketones when it is internal. 

Meyer-Schuster rearrangement. Ammonium vanadate, diphenylsilanedio), and an alkanedicarboxylic acid constitute an efficient catalytic system for the conversion of propargyl alcohols to a,/3-unsaturated aldehydes. 

Although direct oleflnation of l,4-dien-3-ones is synthetically difficult, an indirect route is now available conversion of the carbonyl to the propargyl alcohol, followed by catalytic Meyer-Schuster rearrangement using vanadyl acetoacetate [VO(acac)2]. Asymmetric alkoxyallylation of aldehydes has been achieved using a combined carbocupration-zinc homologation-allylation reaction in one pot. ... 

The addition of alkoxyacetylides to aldehydes and ketones has emerged as a powerful olefination strategy for the production of a,p unsaturated carboxylic esters. This technique was first reported in the synthesis of an antifungal mold metabolite isolated from the fermentation of an acrostalagmus species. Addition of the acetylide anion to 28 and subsequent Meyer-Schuster rearrangement completed the synthesis of the metabolite 29 along with its anomer 30. 

DFT study of interception of the allenyl enolate intermediate of Meyer-Schuster rearrangement using aldehydes and imines has shown that the active form of the vanadium catalyst bears two triphenyl siloxy ligands and that vanadium enolate is directly involved in the C-C bond formation." DFT calculations have elucidated the mechanisms and diastereoselectivities of phosphine-catalysed [4-1-2] annulations between allenoates and ketones or aldimines (Scheme 44). 

The transient allenyl enolate intermediate of the vanadium-catalysed Meyer-Schuster rearrangement with aldehydes and imines has been studied computationally and the active form of the catalyst is considered to contain two triphenylsiloxy ligands. The transesterification of vanadate occurs via tr-bond metathesis and the vanadium enolate is directly involved in the key C-C bond formation (Scheme 175). ... 

---