Tandem: Allylic alcohols react with N‐chlorosuccinimide (NCS) in a tandem 1,3‐H shift/CCl bond formation leading to α‐chloroketones and α‐chloroaldehydes. The reactions proceed with complete selectivity to give single constitutional isomers of monochlorinated carbonyl compounds. The utility of the transformation is illustrated by the straightforward synthesis of 4,5‐disubstituted 2‐aminothiazoles
Olefin-Metathesis-Based Synthesis of Furans by an RCM/Deprotonation/Phosphorylation Sequence and Their Diels-Alder Reactions
作者:Bernd Schmidt、Diana Geißler
DOI:10.1002/ejoc.201101078
日期:2011.12
Butenolides, obtained by ring-closing metathesis (RCM) of acrylates, undergo quantitative deprotonation with amide bases. Trapping of the resulting anions with electrophiles, for example, chlorophosphates, give furans. Subsequent Diels–Alderreaction and acid-catalysed rearrangement of the resulting oxabicyclonorbornadienes give substituted benzenes.
Cross metathesis of allyl alcohols: how to suppress and how to promote double bond isomerization
作者:Bernd Schmidt、Sylvia Hauke
DOI:10.1039/c3ob40167g
日期:——
formation of ketones, resulting from uncontrolled and undesired doublebondisomerization. By conducting the CM in the presence of phenol, the catalyst loading and the reaction time required for quantiative conversion can be reduced, and isomerization can be suppressed. On the other hand, consecutive isomerization can be deliberately promoted by evaporating excess methyl acrylate after completing cross
Stereoselective Synthesis of 2Z,4E-Configured Dienoates through Tethered Ring Closing Metathesis
作者:Bernd Schmidt、Stephan Audörsch、Oliver Kunz
DOI:10.1055/s-0035-1562536
日期:——
is described. The sequence involves Steglich esterification of the reactants, followed by a one-pot ringclosing metathesis–base induced elimination–alkylation reaction to furnish the products in high stereoselectivity. Trapping of the intermediate sodium carboxylates is accomplished efficiently using Meerwein’s salt Et3OBF4. A two-step sequence leading from racemic allylic alcohols and vinylacetic
A simple asymmetrictotalsynthesis of stagonolideG (1) is described. Asymmetric dihydroxylation, regioselective epoxide ring opening, and vinyl Grignard reactions are involved in generating the stereogenic centers C(4) and C(8), followed by Grubbs‐II‐catalyzed ring‐closing metathesis (RCM).