Synthesis of Acylsilanes via Nickel-Catalyzed Reactions of α-Hydroxyallylsilanes
摘要:
The redox isomerization processes and tandem isomerization-aldolization reactions, mediated by nickel catalysts, offer new versatile entries to acylsilanes. For the second reaction, high diastereoselectivities, up to 98:2, have been obtained with bulky substituents on silicon.
A short approach toward new acrolein‐type derivatives, functionalized in position 2 is described. It involves, as the key step, a smooth transformation of acylsilanes into aldehydes by irradiation in water‐organic solvent mixtures. The functionalized enals obtained by this newroute appear as versatile building blocks for the preparation of natural products and/or bioactive compounds.
A controllable Rh-catalyzed protocol to access alkylation and akenylation-annulation off N-tosyl acrylamide with, acryloyl silane is reported. In contrast to the directing group or catalyst-dependent divergent sp(2) C-H alkylation/alkenylation the instrinsic property of acryloylsilane allows the switchable reaction manifold, thereby affording either alkylation or alkylation Products with slight modification of the reaction conditions.
α-Hydroxyallylsilanes as Propionaldehyde Enolate Equivalents and Their Use toward Iterative Aldol Reactions
Smooth and efficient reaction conditions have been found for the transformation of protected beta-hydroxyacylsilanes into the corresponding aldehydes. This opens a new route to iterative aldol reactions, and it has been used for the synthesis of fragments of several bioactive natural products.