Intramolecular cyclizations of α-stannyl radicals to acylsilanes: regiospecific syntheses of five-membered cyclic silyl enol ethers
作者:Yeun-Min Tsai、Sheng-Yueh Chang
DOI:10.1039/c39950000981
日期:——
α-Stannyl radicals generated from acylsilanes 5, 13 and 14 cyclize to give good yields of cyclic silyl enol ethers after sequential cyclizations, radical Brook rearrangements and β-scissions.
terminal alpha-stannyl bromide or xanthate functionalities are prepared. Alpha-stannyl radicals generated from these acylsilanes undergo intramolecularcyclizations to give cyclic silyl enol ethers regiospecifically. The radical processes involve radical cyclization, Brook rearrangement, and beta-fragmentation in sequence. A tributylstannyl group serves as the radical leaving group. The newly formed
A New Strategy for Construction of Eight-Membered Carbocycles by Brook Rearrangement Mediated [6 + 2] Annulation
作者:Kei Takeda、Hidekazu Haraguchi、Yasushi Okamoto
DOI:10.1021/ol0353767
日期:2003.10.1
text] A newly developed strategy for construction of eight-memberedcarbocycles via [6 + 2] annulation that involves the combination of beta-alkenoyl acylsilanes and a vinyllithium derivative is described. A unique feature of this annulative approach is that it enables in one operation and a stereoselective manner construction of eight-membered ring systems containing useful functionalities for further
A mild protocol for hydroacylation of enones through photosensitization of acyl silanes with thioxanthone under blue light (455 nm) irradiation is reported. A Brønsted acid is used as a cocatalyst in the reaction. The versatility of the method is demonstrated through inter- and intramolecular hydroacylation reaction. The hydroacylation product is applied for synthesizing an anti-HCV agent. Mechanistic