Bifunctional annulating reagents: The use of novel allylsilanes for the one-pot preparation of six and seven-membered rings

Cascade Annulation Reactions To Access the Structural Cores of Stereochemically Unusual Strychnos Alkaloids

“…[13][14][15] Tryptophol (26) was condensed with carboxylic acid 7 to give ester 27 (Scheme 4). Conversion to the mixed acetal followed by BF 3 ·OEt 2 -promoted cyclization provided tetrahydrofuran analogue 28 in good yield (64 %).…”

A Novel [5+2] Cycloaddition Reaction Using a Dicobalt Acetylene Complex

“…From the viewpoint of efficiency, a cycloaddition approach which produces two C−C bonds in one stage is advantageous. In this regard, [4+3]-type annulation reactions of dienes and allyl cationic species have been widely examined, while much less attention has been given to a [5+2] cycloaddition approach. − …”