γ-Regioselectivity of (furan-2-yloxy)-trimethyl-silane towards iminium salts: synthesis of γ-arylidenebutenolides

Abstract

The aminoalkylation of (furan-2-yloxy)trimethylsilane (1) from inexpensive starting materials yields γ-butenolides 4. Preformed and in situ generated ternary iminium salts are used. In contrast to other methodologies, no mercury or silver catalysts are necessary for this procedure.

Divergent Synthetic Strategy Leading to Structurally Diverse Pyrrolidines and Piperidines from Common γ-Aminoalkyl Butenolide and Aldehyde Precursors

“…Acidic removal of the Boc-protecting group afforded the free amines 9 and 10 , which needed to be handled with care. Thus, they have a tendency to epimerize, particularly in the absence of solvent, and this is also accompanied by gradual decomposition . Nevertheless, we have been able to isolate pyrrolidine 9a in 84% yield and characterize it as the partially epimerized material.…”

Synthesis of Heterocycles Mediated by Benzotriazole. 1. Monocyclic Systems

“…The isomer ratio Z : E is 77:23. The isomers are readily separated by column chromatography (Scheme ) …”

Asymmetric Synthesis of Ramariolides A and C through Bimetallic Cascade Cyclization and Z–E Isomerization Reaction

“…Though few sporadic reports for the synthesis of the γ-( Z )-butenolide scaffolds are known, Lu’s procedure was superior and extremely versatile in terms of its selectivity (regio- and diastereoselectivity) and atom economy. Stereochemical information present in the precursor (existing stereocenter in the alkyne fragment) was unaffected by this tandem cross-coupling/lactonization method.…”