Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Ring closing metathesis olefins

Later Grubbs discovered ruthenium carbene complex and used it for a metathesis reaction to synthesize cyclic compounds 5a-d [Eqs. (6.4) and (6.5)]. In 1995, Grubbs found that ruthenium benzylidene carbene complex Ic, which is now commercially available, has the same reactivity as that of lb. Many researchers have therefore used this complex for olefin metathesis, and this reaction has been useful for the synthesis of carbo- and heterocyclic compounds and fused bicyclic compounds [Eq. [6.6)] ° [Pg.155]

Crimmins reported the synthesis of enantiomerically pure cyclopentenol derivative 8 from diene 6 using ring-closing olefin metathesis followed by treatment with UBH4 [Eq. (6.7)]  [Pg.156]

Furstner succeeded in the synthesis of dactylol using ring-closing metathesis of 9d. Crimmins synthesized enantioselectively diene 9e, and RCM of 9e gave eight-membered ring compound lOe, which is an intermediate for the synthesis of laurencin [Eq. (6.12)]  [Pg.157]

For the synthesis of C2-symmetric 1,4-diol, Evans planned temporary silicon-tethered ring-closing metathesis, and asymmetric synthesis of D-altritol was [Pg.157]

Metathesis of a diene containing silicon atoms gives an interesting cyclic compound, whose silicon moiety can be converted into the hydroxyl group by Tamao oxidation [Eqs. (6.14) and (6.15)]  [Pg.158]


Acyclic diene molecules are capable of undergoing intramolecular and intermolec-ular reactions in the presence of certain transition metal catalysts molybdenum alkylidene and ruthenium carbene complexes, for example [50, 51]. The intramolecular reaction, called ring-closing olefin metathesis (RCM), affords cyclic compounds, while the intermolecular reaction, called acyclic diene metathesis (ADMET) polymerization, provides oligomers and polymers. Alteration of the dilution of the reaction mixture can to some extent control the intrinsic competition between RCM and ADMET. [Pg.328]

Scheme 8.16. Examples of the Ring-Closing Olefin Metathesis Reaction... Scheme 8.16. Examples of the Ring-Closing Olefin Metathesis Reaction...
The aggregation pheromone of the broad-horned flour beetle (Gnatocerus cornutus) was reported to be (lJR,4i, 5S)-(+)-acoradiene (33) by Tebayashi et al. [72]. Scheme 47 shows Mori s synthesis of (lRy4Ry5S)-33 [73]. The key-step was the ring-closing olefin metathesis of A to give B. An X-ray analysis of C confirmed the structure shown. The product (lJR,4JR,5S)-33, however, was different... [Pg.32]

Grubbs applied his ring-closing olefin metathesis reaction to the synthesis of (lS,5R)-44 as shown in Scheme 67 [99]. The key-step was the cyclization of A to give C. The unreacted anti-isomer B could be recovered and equilibrated to a mixture of A and B. [Pg.48]

Tandem carbonyl olefmation—olefm metathesis utilizing the Tebbe reagent or dimethyl-titanocene is employed for the direct conversion of olefmic esters to six- and seven-mem-bered cyclic enol ethers. Titanocene-methylidene initially reacts with the ester carbonyl of 11 to form the vinyl ether 12. The ensuing productive olefm metathesis between titano-cene methylidene and the cis-1,2 -disubstituted double bond in the same molecule produces the alkylidene-titanocene 13. Ring-closing olefin metathesis (RCM) of the latter affords the cyclic vinyl ether 14 (Scheme 14.8) [18]. This sequence of reactions is useful for the construction of the complex cyclic polyether frameworks of maitotoxin [19]. [Pg.478]

Another synthetic application of olefin metathesis using a thioacetal-titanocene(II) system is the ring-closing olefin metathesis (RCM) of carbene complexes possessing an olefin moiety, e. g. 33 (Scheme 14.17). The success of the RCM apparently depends on the substituents at the carbon—carbon double bond (i. e. the substituent(s) on the resulting carbene complex 34). [Pg.481]

Advent of ring-closing olefin metathesis reaction has influenced the synthetic strategy of pheromones very much. For example, the racemate of a macrolide pheromone such as (5Z,13S)-5-tetradecen-13-olide (29) (aggregation pheromone of the flat grain beetle, Cryptolestes pusillus) could readily be synthesized as shown in Scheme 42 [67]. Unfortunately, ( )-29 prepared by this method was a mixture of c/s, trans-isomers (Z/E=69 31). (S)-5-Hexadecanolide (27) was also synthesized by means of ring-closing olefin metathesis as shown in Scheme 43 [68]. [Pg.26]

Fiirstner A, Muller T (1999) Efficient Total Syntheses of Resin Glycosides and Analogues by Ring-Closing Olefin Metathesis. J Am Chem Soc 121 7814... [Pg.152]

These reactions involve metallate rearrangements , migratory insertion and transition metal-catalysed vinylic substitution reactions. They also perform well in applications in natural product synthesis . Many useful synthetic possibilities arise from application of ring-closing olefin metathesis (RCM) to unsaturated homoaldol products and their derivatives by means of the Grubbs catalyst 3942 4-286 Equation 105 presents some examples. ... [Pg.1136]

Ring-closing Olefin Metathesis for Organic Synthesis... [Pg.207]


See other pages where Ring closing metathesis olefins is mentioned: [Pg.144]    [Pg.158]    [Pg.6]    [Pg.30]    [Pg.509]    [Pg.516]    [Pg.516]    [Pg.375]    [Pg.174]    [Pg.381]    [Pg.164]    [Pg.10]    [Pg.10]    [Pg.14]    [Pg.501]    [Pg.2]    [Pg.97]    [Pg.155]    [Pg.359]   
See also in sourсe #XX -- [ Pg.26 , Pg.28 , Pg.44 ]

See also in sourсe #XX -- [ Pg.174 , Pg.252 , Pg.341 , Pg.343 ]

See also in sourсe #XX -- [ Pg.26 , Pg.28 , Pg.44 ]

See also in sourсe #XX -- [ Pg.433 , Pg.434 ]

See also in sourсe #XX -- [ Pg.282 , Pg.285 ]

See also in sourсe #XX -- [ Pg.52 , Pg.55 , Pg.59 ]




SEARCH



Dienes ring-closing metathesis, olefin

Epothilones ring-closing olefin metathesis strategy

Macrocyclic natural products olefin ring-closing metathesis

Macrolactone ring-closing olefin metathesis

Olefin metathesis

Olefin ring-closing

Olefine metathesis

Olefins enyne ring closing metathesis

Olefins ring-closing olefin metathesis

Relay ring-closing metathesis, olefins

Ring metathesis

Ring-Closing Olefin Metathesis (RCM)

Ring-closed

Ring-closing

Ring-closing metatheses

Ring-closing metathesi

Ring-closing olefin metatheses 12- member

Ring-closing olefin metathesis reaction

Ruthenium catalysts olefin ring-closing metathesis

Ruthenium-catalyzed ring-closing olefin metathesis

Sequences Initiated by Ring-Closing Olefin Metathesis

© 2024 chempedia.info