已经开发了3-氨基-4-羟基六氢嘧啶-2-硫酮的碱促进的环扩展成2,4,5,6-四氢-3 H -1,2,4-三氮杂-3-硫酮。实验数据和DFT计算表明,反应是通过快速形成嘧啶的中间体无环异构体,然后缓慢环化为三氮杂s而进行的。通过使α,β-不饱和酮或β-烷氧基酮与HNCS反应,然后用肼处理所获得的β-异硫氰酸根酮来制备起始羟基嘧啶。通过在碱性条件下用H 2 O 2氧化将三氮杂-3-硫酮转化为它们的3-氧代类似物。
Trimethysilyl triflate in organic synthesis11Part 11 of this series. Part 10: S. Murata and R. Noyori, Tetrahedron Letters 2107 (1981).
作者:R. Noyori、S. Murata、M. Suzuki
DOI:10.1016/s0040-4020(01)93263-6
日期:——
Trimethylsilyl triflate is a powerful silylating agent for organic compounds and acts as a catalyst which accelerates a variety of nucleophilic reactions in aprotic media. The reactions proceed via one-center, electrophilic coordination of the silyl group to hetero functional groups and exhibit unique selectivities.
Bistrifluoromethanesulfonimide has been used to catalyze C-C bondforming reactions such as Friedel-Crafts, Mukaiyama, 1,2-addition and 1,4-addition as well as C-glycosidation reactions.
双三氟甲磺酰亚胺已用于催化 CC 键形成反应,例如 Friedel-Crafts、Mukaiyama、1,2-加成和 1,4-加成以及 C-糖苷化反应。
Trimethylsilyl trifltate catalyzed aldol-type reaction of enol silyl ethers and acetals or related compounds
作者:Shizuaki Murata、Masaaki Suzuki、Ryoji Noyori
DOI:10.1016/s0040-4020(01)86671-0
日期:1988.1
condensation of enol trimethylsllyl ethers with acetals, orthoformate, or 2-acetoxytetrahydrofuran or -pyrans to give the corresponding β-alkoxy carbonylcompounds. Reaction of enolsilylethers and carboxonium triflate ion-pair intermediates occurs via acyclic transition states and exhibits moderate to high erythro selectivity independent of the geometry (E/Z) of the enolsilylethers.
A new catalyst trimethylsilyl bis(fluorosulfonyl)imide has been prepared for aldol type reactions and allylation of acetals. The catalyst has been found to be more active than trimethylsilyl triflate for the above reactions.