烯烃的交叉复分解反应(CM)及其合成应用

概述了近年来烯烃交叉复分解反应的研究进展及其在有机中间体制备、碳水化合物的合成、高分子化学以及工业生产上的应用.     

Cross-metathesis of α-methylene-β-lactams: the first tetrasubstituted alkenes by CM

α-Alkylidene-β-lactams have been prepared in good to excellent yields by olefin cross-metathesis. Electron-poor α-methylene-β-lactams undergo cross-metathesis more rapidly and efficiently than more electron-rich analogs. Significantly, tetrasubstituted alkenes have for the first time been accessed by CM reactions.     

Microwave-accelerated cross-metathesis reactions of N-allyl amino acid substrates

Microwave heating has been utilised for the cross-metathesis reaction of N-allyl amino acid substrates to generate olefin homodimers. Remarkable acceleration of the cross-metathesis reaction (minutes compared to hours) over conventional reflux heating was observed. In addition, improved reaction yields and similar E/Z ratios for the cross-metathesis products were achieved.     

Synthesis of the pro-gly dipeptide alkene isostere using olefin cross-metathesis

An approach to the synthesis of dipeptide olefin isosteres using intermolecular olefin cross-metathesis is presented. In particular, a synthesis of the Pro-Gly isostere (1) is reported. Conversion of N-BOC-proline into the corresponding vinyl-substituted carbamate provides the N-terminal cross-metathesis partner (2). Methyl 3-butenoate (3) is employed as the C-terminal component. Treatment of the two partners in an optimized molar ratio affords the cross product 1 (83% yield). Three other examples are demonstrated to evaluate the potential of the approach.     

Recent developments in olefin cross-metathesis

Among the many types of transition-metal-catalyzed C-C bond-forming reactions, olefin metathesis has come to the fore in recent years owing to the wide range of transformations that are possible with commercially available and easily handled catalysts. Consequently, olefin metathesis is now widely considered as one of the most powerful synthetic tools in organic chemistry. Until recently the intermolecular variant of this reaction, cross-metathesis, had been neglected despite its potential. With the evolution of new catalysts, the selectivity, efficiency, and functional-group compatibility of this reaction have improved to a level that was unimaginable just a few years ago. These advances, together with a better understanding of the mechanism and catalyst-substrate interactions, have brought us to a stage where more and more researchers are employing cross-metathesis reactions in multistep procedures and in the synthesis of natural products. The recent inclusion of alkynes and hindered bicyclic olefins as viable substrates for bimolecular metathesis coupling, the discovery of enantioselective cross-metathesis and cross-metathesis in water, and the successful marriage of metathesis and solid-phase organic synthesis has further widened the scope of this versatile reaction.     

Olefin cross-metathesis with vinyl halides

The first successful example of olefin cross-metathesis with chloroalkenes is reported.     

Chemoselective construction of substituted conjugated dienes using an olefin cross-metathesis protocol

[Reaction: see text] Various substituted conjugated dienes have been made by olefin cross-metathesis. Using either electronic or steric "protection," one of the olefins of the conjugated diene was deactivated relative to the other for cross-metathesis. The reactions proceed with very high chemoselectivity and, when steric deactivation is used, very high diastereoselectivity.     

Solid-phase olefin cross-metathesis promoted by a linker

Olefin cross-metathesis couples two alkenes to form complex molecules and has been widely used in solution-phase organic synthesis. However, this powerful method has rarely been used in solid-phase organic synthesis. Herein we report that olefin cross-metathesis is a synthetically viable method particularly when a traceless longer linker is inserted between solid support and reacting olefins.     

Application of olefin cross-metathesis to organometallics. Synthesis of unsaturated ferrocenyl alcohols and ketones

[reaction: see text] The application of olefin cross-metathesis to terminally unsaturated alpha-hydroxy- and alpha-ketoferrocenes is reported. Both substrates provided the terminally functionalized olefins in moderate to good yield. These examples represent the first cases of cross-metathesis of substrates containing an organometallic functional group.     

Cross-metathesis, a versatile synthetic methodology for the construction of alkenyl phosphine oxides and bis-phosphine oxides

Substituted vinyl and allyl phosphine oxides have been prepared by olefin cross-metathesis providing exclusive E olefin stereochemistry. The methodology has been successfully extended to the preparation of various bis-phosphine oxides.     

Synthesis of chlorophyll a glycoconjugates using olefin cross-metathesis

Chlorophyll a glycoconjugates were obtained by cross-metathesis between olefin moieties of chlorophyll derivatives and allylβ-galactopyranoside tetraacetate.     

Highly demanding cross-metathesis in the synthesis of the C16-C30 fragment of dolabelide C

A highly demanding cross-metathesis (CM) reaction for the formation of the C24-C25 trisubstituted olefin of dolabelide C has been optimized. A difference in reactivity between the E and Z enone isomers in this reaction was uncovered, and the selection of the Z isomer of the starting enone was critical for the success of the cross-metathesis. Application to the synthesis of the C16-C30 fragment of dolabelide C is reported.     

Exploiting site-site interactions on solid support to generate dimeric molecules

[structure: see text]. "Intra-site" olefin cross-metathesis on solid support leads to nearly quantitative yields of dimeric molecules.     

Total synthesis of dermostatin A

The concise total synthesis of dermostatin A is described. Highlights include a two-directional application of the asymmetric acetate aldol method developed in our lab, a novel diastereotopic-group-selective acetal isomerization for terminus differentiation, and a selective cross-metathesis reaction between a terminal olefin and a trienal. A study of the scope and viability of similar cross-metathesis reactions is also described. The synthesis is convergent and utilizes fragments of roughly equal complexity.     

Synthesis of functionalized vinyl boronates via ruthenium-catalyzed olefin cross-metathesis and subsequent conversion to vinyl halides

Functionalized vinyl pinacol boronates suitable for Suzuki cross-coupling reactions are synthesized using ruthenium-catalyzed olefin cross-metathesis of 1-propenyl pinacol boronate and various alkenes, including functionalized and 1,1-disubstituted alkenes. The resultant boronate cross products are stereoselectively transformed into predominantly Z-vinyl bromides and E-vinyl iodides. The vinyl bromides may be synthesized in a two-step, one-pot synthesis from a variety of olefins, resulting in a Z-selective formal vinyl bromide cross-metathesis reaction.     

Stereoselective total synthesis of alkaloid caulophyllumine B using iterative olefin cross-metathesis protocol

Herein we report the first total synthesis of alkaloid caulophyllumine B in 14 steps by an iterative olefin cross-metathesis strategy from l-glutamic acid.     

Ruthenium-catalyzed tandem cross-metathesis/Wittig olefination: generation of conjugated dienoic esters from terminal olefins

[reaction: see text] In the presence of ruthenium-based olefin metathesis catalysts and triphenylphosphine, alpha,beta-unsaturated aldehydes can be olefinated with diazoacetates. This ruthenium-catalyzed transformation has been employed in tandem with olefin cross-metathesis to convert terminal olefins into 1,3-dienoic esters in a single operation.     

An efficient synthesis of D-erythro- and D-threo-sphingosine from D-glucose: olefin cross-metathesis approach

[reaction: see text] The D-erythro- and D-threo-sphingosine were synthesized via E-selective olefin cross-metathesis using a D-glucose-derived building block and long-chain terminal alkene.     

Iterative synthesis of heterotelechelic oligo(phenylene-vinylene)s by olefin cross-metathesis

A novel iterative synthesis of heterotelechelic oligo(phenylene-vinylene)s using olefin cross-metathesis is reported. The metathesis homologation proceeds in good yields and allows for further functionalization, including the facile formation of donor-acceptor complexes and repeating sequence copolymers.     

Cross-metathesis reactions of vinyl-chlorins and -porphyrins catalyzed by a "second generation" Grubbs' catalyst

The first application of olefin cross-metathesis with vinylchlorins and vinylporphyrins using a "second generation" Grubbs' catalyst is reported. Cross-metathesis products were obtained in good yields with high E-stereoselectivity.