The [2+2]-Photocycloaddition of Aromatic Aldehydes and Ketones to 3,4-Dihydro-2-pyridones: Regioselectivity, Diastereoselectivity, and Reductive Ring Opening of the Product Oxetanes
作者:Thorsten Bach、Hermann Bergmann、Harm Brummerhop、Warren Lewis、Klaus Harms
DOI:10.1002/1521-3765(20011015)7:20<4512::aid-chem4512>3.0.co;2-h
日期:2001.10.15
4-Dihydro-2-pyridones [3,4-Dihydropyridin-2(1H)-ones] 6 were evaluated with respect to their use as alkene components in stereoselective Paternò-Büchi reactions. The parent compound 6a was shown to be a versatile synthetic building block that reacted with various photoexcited aromatic carbonyl compounds (benzaldehyde, benzophenone, acetophenone, methyl phenylglyoxylate, 3-pivaloyloxybenzaldehyde) with
评估了3,4-二氢-2-吡啶酮[3,4-二氢吡啶-2(1H)-酮] 6作为立体选择性Paternò-Büchi反应中的烯烃组分的用途。母体化合物6a被证明是一种通用的合成构件,可与多种光激发的芳族羰基化合物(苯甲醛,二苯甲酮,苯乙酮,苯乙醛酸甲酯,3-新戊酰氧基苯甲醛)反应,具有很高的区域和非对映选择性(51-63%产率) 。产物可以进行氢解,为合成2-芳基甲基-3-哌啶子醇开辟了一条新的有效途径。作为实例,将氧杂环丁烷7a和8a氢解裂解,得到产物12(88%)和13(93%)。化合物6a通过两个氢键与手性内酰胺主体结合的能力被有利地用于区分其双键的对映体面。在-10℃下在甲苯中进行的手性醛15的光环加成中,记录了高的非对映选择性(> 90%de.56%收率)。立体选择性是由二氢吡啶酮6a与醛的1:1缔合产生的。发现4-取代的二氢吡啶酮6b-6d(R =甲基,异丙基,苯基)不太适合潜在地用