关环复分解反应(RCM)及其催化剂研究进展

综述了近年来关环复分解 (RCM )反应及其催化剂的研究进展 ,对RCM反应发展以来被广泛应用的催化剂 ,如Schrock催化剂和Grubbs催化剂等进行了归纳和总结 ,讨论了RCM反应在全合成中的应用     

Concise enantioselective synthesis of (−)-lasubine II

An enantioselective synthesis of the quinolizidine alkaloid (−)-lasubine II 1 is reported. Two different pathways to the key intermediate 2 are described. The first case involving a sequence of ring rearrangement metathesis (RRM), simple functional group interconversion operations, followed by a stereoselective cross metathesis (CM) and in the second case a domino ring opening-/ring closing-/cross metathesis step is involved. In both cases, following the metathesis reactions, exclusively the E-isomer was obtained. The final cyclisation towards the quinolizidine skeleton is achieved by an intramolecular Michael reaction. This concept represents the first example of a highly stereoselective RRM-CM combination in the synthesis of a natural product.     

Application of RCM reaction in the construction of ABC ring of micrandilactone A

[reaction: see text] The functionalized ABC ring system of micrandilactone A was successfully constructed in 14 steps. The key reactions in this synthesis are the intermolecular Diels-Alder reaction (IMDA) and the eneyne ring-closing metathesis (RCM) reaction.     

A new approach to (-)-swainsonine by ruthenium-catalyzed ring rearrangement

A new enantioselective synthesis of the idolizidine alkaloid (-)-swainsonine 1 in 40% overall yield starting from the known oxazolidinone 6 is described. Throughout the synthesis, the high efficiency of metal-catalyzed reactions is illustrated. The key step is a new ruthenium-catalyzed metathesis rearrangement reaction. In this ring-closing/ring-opening tandem process, stereocenters are transferred from a ring to the olefinic side chain of the formed heterocycle. The metathesis precursor was obtained by palladium-catalyzed desymmetrization of cyclopentenediol. The synthesis was completed by functionalization of the terminal double bond, cyclization of the second ring, and diastereoselective dihydroxylation.     

Studies directed toward the synthesis of the scabrosins: validation of a tandem enyne metathesis approach

A synthetic approach to the scabrosin family of antibiotics using a ruthenium carbene-catalyzed tandem metathesis and a Pd(II)-catalyzed cyclization is described. The chiral propargyl amino acid is furnished through enantioselective phase-transfer propargylation. The synthesis of the cyclohexadiene ring system is achieved through ring synthesis using tandem enyne metathesis, previously developed in our lab. The complementary methods of methylene-free and 1,5-hexadiene-alkyne metatheses are compared. The indoline heterocycles are formed using a two-step chloroacetoxylation (Bäckvall reaction) with subsequent nucleophilic attack by an amide nucleophile. The indoline subunits were joined and cyclized to furnish the core diketopiperazine ring. The stereochemical assignment of intermediates is also discussed.     

Microwave-enhanced synthesis of N-shifted buflavine analogues via a Suzuki-ring-closing metathesis protocol

[reaction: see text] A novel, microwave-enhanced six-step synthesis was devised for the synthesis of N-shifted buflavine analogues. Microwave-enhanced Suzuki-Miyaura cross-coupling and ring-closing metathesis reactions were used as the key steps. Microwave irradiation was found to enhance the ring-closing metathesis reaction to generate the otherwise difficultly obtainable medium-sized ring system of the target molecules.     

Synthesis of phosphorus containing medium ring heterocycles by sequential Claisen rearrangement and ring closing metathesis

An efficient method for the synthesis of novel medium ring phosphorus containing heterocycles starting from phenol derivatives by ruthenium catalyzed ring closing metathesis is described. This work deals with a sequential aromatic Claisen-rearrangement, coupling of an allyl/vinyl phosphonate, and ring closing metathesis reaction. All of these reactions were carried out at ambient temperature to afford the medium-sized phosphorus heterocycles in excellent yields.     

Ring closing enyne metathesis: a powerful tool for the synthesis of heterocycles

The ring closing metathesis (RCM) is a powerful method in organic synthesis for the preparation of cyclic compounds by formation of new carbon-carbon bonds. In the past years a particular subclass of the RCM, the ring closing enyne metathesis (RCEYM), has attracted attention due to its synthetic potential in the generation of ring structures with 1,3-diene moieties, which can subsequently be further functionalised. In this tutorial review mechanistic considerations will be described and the synthetic power of this useful and attractive carbon-carbon bond forming reaction will be illustrated by recent examples of RCEYM applications in the preparation of heterocyclic compounds.     

Enantio- and stereospecific syntheses of 15(R)-Me-PGD2, a potent and selective DP2-receptor agonist

The first total synthesis of 15(R)-Me-PGD2 3 is reported. The synthesis is based on the enantioselective and stereospecific syntheses of synthon 17 and its attachment to the five-membered ring by a olefin cross metathesis reaction. This approach permits the introduction of a side chain with a predetermined stereogenic center into the prostanoid ring, resulting in the synthesis of 15R-methyl prostaglandin D2 and allows rapid access to other prostanoids.     

Observations in the synthesis of the core of the antitumor illudins via an enyne ring closing metathesis cascade

Observations concerning the synthesis of the core spirocyclic AB-ring system of illudins using an enyne ring closing metathesis (EYRCM) cascade are discussed. Substituent effects, in addition to optimization of the reaction conditions and the olefin tether for the key EYRCM reaction, are examined.     

Stereoselective synthesis of (−)-allosedamine and (1R,3R)-HPA-12 from β-p-toluenesulfonamido-γ,δ-unsaturated sulfoxide

A stereoselective synthesis of (−)-allosedamine and HPA-12 is disclosed. The key steps of the synthesis include the diastereoselective synthesis of a β-sulfonamido unsaturated sulfoxide, elaboration of a bromohydrin via intramolecular sulfinyl group participation and a ring-closing metathesis reaction for the construction of the piperidine ring of allosedamine.     

Stereoselective total synthesis of (-)-perrottetinene and assignment of its absolute configuration

The first stereoselective total synthesis of the bibenzyl tetrahydrocannabinol, (-)-perrottetinene, has been achieved from readily available starting materials. The absolute stereochemistry is derived from a chiral gamma-hydroxy vinylstannane. The key reaction is the synthesis of the cis-disubstituted cyclohexene ring of perrottetinene by diastereoselective Ireland-Claisen rearrangement and a ring-closing metathesis reaction. The absolute configuration of (-)-perrottetinene is proposed.     

Total synthesis of the neotropical poison-frog alkaloid (-)-205B

[reaction: see text]. A stereocontrolled total synthesis of the neotropical poison-frog alkaloid (-)-205B (1) has been achieved, employing a dithiane three-component linchpin coupling, a one-pot sequential construction of the embedded indolizidine ring, and ring-closing metathesis (RCM) to arrive at the novel 8b-azaacenaphthylene ring system comprising the alkaloid. The synthesis proceeded with a longest linear sequence of 19 steps, affording (-)-1 in 5.6% overall yield.     

过渡金属催化的6-苯基-5,6-二氢-2H-吡喃-2-酮的合成——推荐一个大学有机化学综合实验

有机合成中,碳-碳键的形成和断裂是一个永恒的热门话题,科学家为此发展了很多形成碳-碳键的方法。在这一领域,诞生了不少诺贝尔化学奖的成果,格氏反应和烯烃复分解反应就是其中的经典案例。烯烃复分解反应提供了一种连接sp2-碳和sp2-碳的全新思路,发展出了一些活性分子全合成的高效路径。因而,2005年的诺贝尔化学奖授予了对烯烃复分解反应有杰出贡献的三位科学家。本有机化学综合实验由三个反应构成,包括改进的格氏反应、DMAP催化的酯化反应和关环烯烃复分解反应。每一个反应都可独立成为一个基础有机化学实验,三步的连续反应可以作为一个综合多步合成实验。本实验有助于理解有机合成的过程和机理,体验有机合成的魅力。     

A rapid formal synthesis of the macrolide (−)-A26771B

(−)-A26771B, a novel 16-membered macrolide with antibiotic activity, has been formally synthesized. In the synthesis ruthenium catalyzed ring-closing olefin metathesis (RCM) was used as a key reaction to construct the lactone ring.     

cis-decalins from quinic acid: toward a synthesis of branimycin

[reaction: see text] Starting from (-)-quinic acid an efficient synthesis of highly functionalized cis-alpha,beta-unsaturated ketone 3, an advanced precursor of branimycin, has been accomplished via two key step reactions: a ring closing metathesis reaction to prepare the cis-decalin system, and a highly stereoselective epoxidation reaction.     

Variable and stereoselective synthesis of azasugar analogues by a ruthenium-catalyzed ring rearrangement

A novel ruthenium-catalyzed ring opening/ring closing tandem metathesis reaction with a catalytic transfer of stereocenters from a ring to an olefinic chain is described. This ring rearrangement serves as the key step in the stereoselective synthesis of the new azasugar analogues 1 and 2.     

Stereoselective total synthesis of (−)-synrotolide diacetate from d-ribose

Stereoselective total synthesis of synrotolide as its diacetate from d-ribose utilizing a diastereoselective Grignard reaction, preferential (Z)-Wittig olefination, asymmetric allylation, and ring closing metathesis as key steps is reported.     

Discovery of a multi-bond forming, four-step tandem process: construction of drug-like polycyclic scaffolds

A one-pot tandem process involving an Overman rearrangement, ring closing enyne metathesis and a hydrogen bonding directed Diels-Alder reaction has been developed for the efficient diastereoselective synthesis of functionalised amino substituted tetralin and indene ring systems.     

Access to Skipped Polyene Macrolides through Ring-Closing Metathesis: Total Synthesis of the RNA Polymerase Inhibitor Ripostatin B

Rip-Roaring! A convergent total synthesis of antibiotic ripostatin?B was developed. A key step in the synthesis is a metathesis reaction allowing for a ring closure to the labile doubly skipped triene macrolide.