C=C双键与分子氧的氧化裂解产生羰基化合物是化学和药物合成中的一个重要转化。在自然界中,含有第一排过渡金属的酶,特别是血红素和非血红素铁依赖性酶,在环境条件下很容易激活 O 2并以极其精确的方式氧化裂解 C=C 键。然而,该反应对合成化学家来说仍然具有挑战性。只有少数已知的合成金属催化剂允许在 O 2大气压下氧化裂解烯烃,很少有人知道催化未活化烯烃的裂解。在这项工作中,我们描述了一种光驱动、Mn 催化的协议,用于在 1 个大气压的 O 2下将烯烃选择性氧化为羰基化合物。首次使用第一排生物相关金属催化剂,在清洁、温和的条件下,可以将芳香族和各种未活化的脂肪族烯烃氧化成酮和醛。此外,该协议显示出非常好的功能组耐受性。机理研究表明,Mn-oxo 物种,包括不对称的混合价双 (μ-oxo)-Mn(III,IV) 络合物,参与氧化,溶剂甲醇参与 O 2活化,导致oxo 物种的形成。
Osmium Tetroxide-Promoted Catalytic Oxidative Cleavage of Olefins: An Organometallic Ozonolysis
作者:Benjamin R. Travis、Radha S. Narayan、Babak Borhan
DOI:10.1021/ja017295g
日期:2002.4.1
A mild, organometallic alternative to ozonolysis utilizing oxone and OsO(4) is presented. This is a direct oxidation of olefins via the carbon-carbon cleavage of an osmate ester by the action of oxone. Twenty-four different olefins were converted to their corresponding ketones or carboxylic acids in high yields (>80%). Free alcohols, acetate- and benzyl-protected alcohols, and 1,2-diols were stable
Disclosed herein are the novel insect repellents of formula (I) to control the spread of various tropical diseases and to the process of preparation thereof wherein R, Rl, R3, R4 represents hydrogen or alkyl; R2 is selected from hydrogen, alkyl, C02R, C02H; 'n' is 1, 2, or 3; wherein any two of Rl, R2, R3 or R4 may form a 3-8 membered carbocyclic ring which may optionally be substituted or may contain a heteroatom; X is selected from O, S or CH2; ' ' represents a single or double bond; wherein, either of the ring in formula (I) may additionally contain at least one carbonyl group.
Biotransformations of the sesquiterpene ketone nootkatonefrom the crude drug Alpiniae Fructus and grapefruit oil, and the sesquiterpene hydrocarbon valencenefrom Valencia orange oil were carried out with microorganisms such as Aspergillus niger, Botryosphaeria dothidea, and Fusarium culmorum to afford structurally interesting metabolites. Their stereostructures were established by a combination of