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Cydopropanations intramolecular

Hodgson et al. showed that a series of bis- and tris-homoallylic terminal epoxides underwent intramolecular cydopropanation to give a range of bicydic alcohols. A short asymmetric synthesis of sabina ketone based on this chemistry was demonstrated (Scheme 5.20). A practical advantage with this process is that the volatile epoxides can be replaced with readily available chlorohydrins, an extra... [Pg.155]

Fig. 2.22. Intramolecular cydopropanation reactions with in-situ-generated alkylidene complexes [46],... Fig. 2.22. Intramolecular cydopropanation reactions with in-situ-generated alkylidene complexes [46],...
Complete cu-selectmty was obtained by intramolecular cydopropanation of unsaturated diazoesters with the subsequent hydrolysis of the lactone obtained, followed by a dchydrohalugcnation step to give (37, X—CHj, Y=C1, Br) (51). [Pg.280]

Cha and coworkers [15] described an interesting example of a radical/cation-mediated domino reaction for the stereoselective preparation of bicyclo[5. B.Ojdecan-3-ones 31 using aminocyclopropane 30 as substrate which was prepared by employing an intramolecular Kulinkovich cydopropanation of olefin-tethered amide. [Pg.146]

TABLE 10.17 Stepwise Intramolecular Reaction of Hydrazones with Cydopropanes... [Pg.259]

SuZ-type organocatalytic alkylations have been developed under intramolecular conditions, leading to chiral cydopropanes and cydopentane derivatives under intramolecular conditions and were used in domino transformations as the final step. SN2-type alkylations with phase-transfer alkylations (Chapter 14), Sul-type reactions (Chapter 26), and free radical and dectron-transfer SOMO-alkylations (Chapter 39) are gaining increasing importance in the organocatalytic arsenal. [Pg.727]

In the competition between allylic intramolecular cydopropanation and macrocyclization (Eq. 5.20), the more electrophilic catalyst favors macrocyclization. Doyle has explained this differential selectivity as due to the formation of an intermediate ii-complex between the C-C double bond and the carbene center. The more electrophilic the carbene carbon or the more electron-rich the double bond, the more that this 7t-complex is favored and the more favorable the pathway to macrocyclization [97]. However, thus far few systems have been examined... [Pg.215]

The I/Mg exchange of 3-iodomethyl-l-oxacyclopentanone derivative 243 is followed by an intramolecular nucleophilic substitution and opening of the oxacydopentane ring leads after aqueous work-up to cydopropane derivative 244 (Scheme 4.50) [129]. [Pg.143]


See other pages where Cydopropanations intramolecular is mentioned: [Pg.290]    [Pg.485]    [Pg.209]    [Pg.353]    [Pg.321]    [Pg.26]    [Pg.498]    [Pg.498]    [Pg.277]    [Pg.243]    [Pg.210]    [Pg.721]    [Pg.215]   
See also in sourсe #XX -- [ Pg.572 ]




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Cydopropanations

Cydopropane

Cydopropanes

Intramolecular cydopropanation

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