With the goal to improve the aqueous solubility of lamellarins, the lactone ring in their skeleton was replaced with a lactam moiety in azalamellarins. However, the reported synthetic route produced such derivatives in very low yields. Hence, this study focused on developing an efficient simplified total synthetic scheme that could furnish both azalamellarins and the parent lamellarins from the same pyrrole
An easy entry to isoquinoline alkaloids by aza-Wittig electrocyclic ring-closure
作者:J. Augusto R Rodrigues、Genaro C Leiva、Joana D.F de Sousa
DOI:10.1016/0040-4039(94)02211-s
日期:1995.1
The reaction of phenethyliminophosphorane with arylketenes gave 1-benzyl-3.4-dihydroisoquinolines in good yields. An aza-Wittig type reaction of vinyliminophosphorane with p-toluenesulfonylisocyanate furnished 1-aminoisoquinoline 6 in high yield.
Total Synthesis of Natural and Unnatural Lamellarins with Saturated and Unsaturated D-Rings
作者:Poonsakdi Ploypradith、Thaninee Petchmanee、Poolsak Sahakitpichan、Nichole D. Litvinas、Somsak Ruchirawat
DOI:10.1021/jo061810h
日期:2006.12.1
Twenty-eight natural and unnatural lamellarins with either a saturated or an unsaturated D-ring were synthesized according to our developed synthetic route. The key step involved the Michael addition/ring closure (Mi-RC) of the benzyldihydroisoquinoline and alpha-nitrocinnamate derivatives, which provided the 2-carboethoxypyrrole intermediates in moderate to good yields (up to 78% yield). Subsequent hydrogenolysis/lactonization furnished lamellarins with a saturated D-ring in excellent yields (up to 93% yield). DDQ oxidation of the saturated lamellarin acetates led directly to the corresponding unsaturated analogues in 54-95% yield. In addition, only two steps in our developed strategy require column chromatography.
Mechanistic duality of the side-chain substitution in electrophilic aromatic nitration. Unexpected large difference in deuterium isotope effect kH/kD between the side-chain nitration and nitrooxylation of deuterated p-xylenes
作者:Nobuaki Nonoyama、Masao Iwaya、Hitomi Suzuki
DOI:10.1016/s0040-4039(99)02053-5
日期:2000.1
A large difference in deuterium kinetic isotope effect observed between the side-chain nitration and nitro-oxylation of deuterated p-xylenes, 1,4-(CH3)(CD3)C6H4 and 1,4-(CD3)(2)C6D4, suggests the operation of different mechanisms for these two types of side-chain substitution. (C) 1999 Elsevier Science Ltd. All rights reserved.
A Highly Efficient Synthesis of Lamellarins K and L by the Michael Addition/Ring-Closure Reaction of Benzyldihydroisoquinoline Derivatives with Ethoxycarbonyl-β-nitrostyrenes