立体控制合成的(R,Z)-和(R,E)-14-甲基-8-十六烯在绝对和几何构型上均具有高立体化学纯度,这是通过使用S N 2型开环反应实现的。 (S)-β-甲基-β-丙内酯用于(R)-构型的构建,顺式加成二有机铜酸盐与乙炔以及δ2-乙烯基-δ-戊内酯的S N 2'型开环反应分别引入(Z)-和(E)-双键。
Synthesis of unsaturated lactones via palladium-catalyzed cyclization of alkenoic acids
摘要:
Acyclic and cyclic, aliphatic or aromatic, 4- or 5-alkenoic acids cyclize in high yield to 5- or 6-membered unsaturated lactones using 5 mol % Pd (OAc) 2, 2 equiv of NaOAc, and 1 atm Of O2.
Last‐minute deal: A directlactonisation of ethers and alcoholsontoamides that proceeds at room temperature under mild conditions is reported (see scheme). This allows the effective saving of up to two unproductive, sequential deprotection operations in synthetic sequences. Mechanistic studies are described, and a new “amidestrategy” that exploits the dual robustness/late‐stage selective activation
The Pd(II)-assisted lactonisation of alkenoicacids has been studied. The selectivity, persisting to formation of 5- and 6-membered unsaturated lactones, can be governed by the change of solvent and/or base.
Synthesis of Vinyllactones via Allylic Oxidation of Alkenoic Acids
作者:Jörg Pietruszka、Martina Bischop
DOI:10.1055/s-0031-1289549
日期:2011.11
A one-step access to vinyllactones is described utilizing the Pd-catalyzed allylic oxidation of alkenoic acids. The influence of ring size as well as the olefin configuration is investigated culminating in the synthesis of goniothalamin analogues.
allylic alcohols of ω‐alkenoic acids and derivatives thereof are highly important building blocks for the synthesis of biologically active compounds. The direct enantioselective CH oxidation of linear terminal olefins offers the shortest route toward these compounds, but known synthetic methods are limited and suffer from low selectivities. Described herein is an enzymatic approach using the P450
Starting from vinylpyranoses an iron-catalyzed tandem isomerization–intramolecular aldolization reaction was developed to prepare cyclohexenone derivatives bearing substituents on the double bond, and it has been applied in a short synthesis of 4-epi-gabosines A and B, from D-glucose.