jo500993x_si_003.cif (25.1 kB)
Three-Step Metal-Promoted Allene-Based Preparation of Bis(heterocyclic) Cyclophanes from Carbonyl Compounds
dataset
posted on 2014-07-03, 00:00 authored by Benito Alcaide, Pedro Almendros, M. Teresa Quirós, Carlos Lázaro, M. Rosario TorresA straightforward
metal-mediated method for the synthesis of bis(dihydrofuryl)
cyclophane scaffolds from carbonyl compounds has been developed. The
combination of the dihydrofuran moiety with different heterocycles
such as β-lactams and sugars allows high levels of skeletal
diversity. The process comprises indium-promoted one-pot carbonyl
bis(allenylation) and gold- or palladium-catalyzed double cyclization
in the resulting bis(allenols), followed by selective ruthenium-catalyzed
macrocyclization. In some cases, the method has been successfully
applied to the synthesis of the challenging Z-isomers.
The E- versus Z-stereochemistry
of the metathesis-formed double bonds could not be assigned taking
into consideration the usual coupling constants criteria, but a diagnostic
based on the chemical shifts of the two olefinic protons located at
the macrocyclic double bond was established.