S-Methylidene agents: preparation of chiral non-racemic heterocycles
作者:David C. Forbes、Sampada V. Bettigeri、Samit A. Patrawala、Susanna C. Pischek、Michael C. Standen
DOI:10.1016/j.tet.2008.10.019
日期:2009.1
Reaction of sulfurylide with aldehyde, imine, and ketone functionality affords the desired three-membered heterocycle in excellent yield. The sulfurylide is generated in situ upon decarboxylation of carboxymethylsulfonium betaine functionality. Of the seven carboxymethylsulfonium betaine derivatives surveyed, the highest level of conversion of π-acceptor to heterocycle was obtained with the one having
硫叶立德与醛、亚胺和酮官能团的反应以优异的产率提供所需的三元杂环。在羧甲基锍甜菜碱官能团脱羧后原位生成硫叶立德。在调查的七种羧甲基锍甜菜碱衍生物中,π-受体转化为杂环的水平最高,其中含有S-甲基和S-苯基官能团与硫代乙酸酯衍生物结合。涉及羧甲基锍甜菜碱官能团脱羧的亚甲基氮丙啶化和环氧化以反应方案、转化水平和范围的优势补充了现有技术。虽然在亚胺官能团的氮丙啶化中观察到中等水平的非对映控制,但使用 Jacobsen 的 Co(II)-salen 络合物解析的四种环氧乙烷均以高产率和对映选择性获得。分离出的手性非外消旋环氧乙烷分别以 3-溴-4-甲氧基苯甲醛和 3,4,5-三甲氧基苯甲醛为原料,正式合成 chelonin B 和考布他汀。
Aryl-Substituted Sulfonium Betaines: Preparation and Use in the Epoxidation of Aldehydes
作者:David C. Forbes、Sejal R. Amin、Christie J. Bean、Michael C. Standen
DOI:10.1021/jo061370u
日期:2006.10.1
Thermally induced decarboxylation of carboxymethylsulfonium betaines results in formation of the corresponding sulfur ylides in situ. Decarboxylation rates for a range of arylcarboxymethylsulfonium betaine salts have been determined using NMR spectroscopy, and the efficiency of ylide generation and trapping has been evaluated via methylidene transfer to a range of aldehydes to form epoxides.
Mononuclear Nonheme Iron(III)‐Iodosylarene and High‐Valent Iron‐Oxo Complexes in Olefin Epoxidation Reactions
作者:Bin Wang、Yong‐Min Lee、Mi Sook Seo、Wonwoo Nam
DOI:10.1002/anie.201505796
日期:2015.9.28
High‐spin iron(III)‐iodosylarene complexes are highly reactive in the epoxidation of olefins, in which epoxides are formed as the major products with high stereospecificity and enantioselectivity. The reactivity of the iron(III)‐iodosylarene intermediates is much greater than that of the corresponding iron(IV)‐oxo complex in these reactions. The iron(III)‐iodosylarene species—not high‐valent iron(IV)‐oxo
Sulfur Ylides via Decarboxylation of Carboxymethylsulfonium Betaines: A Novel and Mild Protocol for the Preparation of Oxiranes
作者:David C. Forbes、Michael C. Standen、Derrick L. Lewis
DOI:10.1021/ol034612a
日期:2003.6.1
of sulfur ylides is described. The overall process involves thermal decarboxylation of a carboxymethylsulfonium betaine to give a sulfur ylide that, in the presence of an aldehyde, affords the corresponding terminal oxirane. Yields were found to correlate with the electron deficiency of the aryl aldehyde. In situ generation of betaine in the presence of an aldehyde successfully afforded the desired oxirane
A series of (substituted phenyl)-2, 3, 5, 6-tetrahydro-1H-imidazo [1, 2-a] imidazoles (10) and their 2- or 3-oxo derivatives (20 and 21) were unambiguously prepared. These compounds were evaluated for antihypertensive and diuretic activities. Antihypertensive activity in spontaneously hypertensive rats (SHR) was observed in the series of compounds 10, whereas compounds 20 and 21 did not possess the activity. Diuretic effects in SHR and normotensive rats were observed in both the series of 10 and the 2- or 3-oxo derivatives (20 and 21). The relationship between the activities and the substituents on the phenyl ring is discussed.