ABSTRACT
A rhodium(I) catalyst incorporating the Me-DuPhos ligand promotes enantioselective intermolecular hydroacylation between beta-S-aldehydes and 1,3-disubstituted allenes. The nonconjugated enone products are obtained in good yields and with high enantioselectivities.
Subject(s)
Aldehydes/chemistry , Alkenes/chemistry , Chemistry/methods , Rhodium/chemistry , Carbon/chemistry , Catalysis , Ligands , Metals/chemistry , Models, Chemical , Molecular Structure , Stereoisomerism , TemperatureSubject(s)
Aldehydes/chemistry , Alkenes/chemistry , Alkynes/chemistry , Catalysis , Sulfur/chemistry , Acylation , Hot Temperature , Hydroxylation , Ligands , Molecular Structure , Rhodium/chemistryABSTRACT
The use of beta-S-substituted aldehydes in rhodium-catalyzed intermolecular hydroacylation reactions is reported. Aldehydes substituted with either sulfide or thioacetal groups undergo efficient hydroacylation with a variety of electron-poor alkenes, such as enoates, in Stetter-like processes and with both electron-poor and neutral alkynes. In general, the reactions with electron-poor alkenes demonstrate good selectivity for the linear regioisomer, and the reactions with alkynes provide enone products with excellent selectivity for the E-isomers. The scope of the process was shown to be broad, tolerating a variety of substitution patterns and functional groups on both reaction components. A novel CN-directing effect was shown to be responsible for reversing the regioselectivity in a number of alkyne hydroacylation reactions. Catalyst loadings as low as 0.1 mol % were achievable.
Subject(s)
Aldehydes/chemistry , Alkenes/chemistry , Alkynes/chemistry , Ketones/chemical synthesis , Rhodium/chemistry , Catalysis , Ketones/chemistry , Molecular Structure , StereoisomerismABSTRACT
[reaction: see text]. Beta-thioacetal-substituted aldehydes, which are conveniently prepared from the corresponding ynals, can be combined with a range of alkynes or electron-poor alkenes to deliver intermolecular hydroacylation adducts. The reactions employ [Rh(dppe)]ClO4 as a catalyst and are proposed to proceed via a chelated rhodium acyl intermediate. The thioacetal-containing products can be deprotected to the corresponding ketones or reduced to alkanes in good yields.
