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Synthesis of Allylic Alcohols from Oxazolinyloxiranes Filippo M

Organic chemistry: “ of alkenes”. addition reactions. Addition of OsO4 (osmium ) to achieve . Using to achieve anti . A synthesis problem. The synthetic toolbox. When does hindrance block one face of a planar intermediate?

Organic chemistry: “Hydrogenation and ”. addition reactions. Problems involving degrees of and hydrogenation (addition of H2). E/Z naming of alkenes. Problems involving addition of X2 (). Forming alkenes from alcohols via E1 (dehydration with H2SO4) or E2.

Process for synthesis of steroidal allylic tert. alcohols

Vanadium-Catalyzed Epoxidation of Allylic alcohol by …

Organic chemistry: “Synthesis problems”. Single- and multi-step synthesis problems. (First-semester final exam review session.)

Organic chemistry: “ aromatic substitution”. aromatic substitution of benzene. Substitution through intermediates. Summary of methods for synthesis of phenols. oxidation to carboxylic acids; synthesis problems involving oxidation. Radical

Organic chemistry: “ synthesis and reactions”. of carbons; acidity of alkynes; use of anions as for SN2 reactions and for attack on (). synthesis from by double elimination; synthesis from alkenes by -double . reactions. Hydrogenation of alkynes; hydrogenation of with catalyst to form alkenes; sequential one-electron reduction of alkynes with sodium metal to form trans alkenes. addition of HX to alkynes; addition of X2 to alkynes (). ; ; mercuric ion-catalyzed hydration of alkynes to form

Transcript of Vanadium-Catalyzed Epoxidation of Allylic alcohol

Organic chemistry: “Alkenes: addition of , BH3, X2”. addition reactions. Addition of H2 (hydrogenation). Addition of , with or without peroxides. Addition of BH3 to get alcohols (-oxidation). Addition of X2.

Catalytic activity of VO(acac)2, epoxidation of allylic alcohol, was confirmed through this project.

To allow for a productive CM coupling, the sphingosine head allylic alcohol was protected with a cyclic carbonate moiety and a reactive CM catalyst system, consisting of Grubbs II catalyst and CuI, was employed

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Vanadium-Catalyzed Epoxidation of Allylic ..


and selective oxidation of the resulting allylic alcohol, furnished 1

The synthesis employs a cross-metathesis to unite a sphingosine head allylic alcohol with a long-chain fatty acid alkene that also bears an allylic alcohol group.

Selective oxidation of secondary alcohols ..

10 mL toluene, VO(acac)2 (25 mg, 0.0943 mmol) in a 2-necked RB flask
*TBHP (1.1 mL, 8 mmol): added over 20 minute period
Reflux for an hour -> ice bath (organic layer on top)
Multiple extraction of organic layer with 1N HCl -> 10 mL Na2SO3 -> 10 mL Brine solution -> 10 mL MgSO4
Gravity filtration to collect filtrate -> Proton NMR preparation (50 ul) -> percent yield

Acetylation of E-geraniol
No reflux
E-geraniol (1g, 6.5 mmol), 4 mL DMAP (4-Dimethylaminopyridine), 2.5 mL of Ac2O, 10 mL toluene in a 2 necked RB flask
Stir for 7 minutes -> ice bath
Same multiple extraction steps -> gravity filtration to collect filtrate
Proton NMR preparation (50 ul) -> percent yield
Experimental (Week 2)
TLC (thin layer chromatography)
2% ethyl acetate in hexane prepared (enough for both column and TLC)
Ran TLC with two crude products and E-geraniol
Calculate retention factor, Rf, in respect to solvent front
Separation/purification of product via column chromatography
added 1/8 inch sand -> 10 cm of 220 - 420 mesh silica gel in a burette -> 0.5 cm sand -> make sure sand is evenly spread on top
drained until eluent is at the sand level -> add sample on top of the sand layer carefully
eluted until sample is just below sand level -> add more eluent
eluted for purification
For every 3 aliquots collected, reference retention value, Rf, of crude products and E-geraniol used to determine which aliquots contained desired product
Collected aliquots -> Rotoevap.

CARBONYLATION OF ALLYLIC ALCOHOLS AND SYNTHESIS …

-> Prep for proton NMR of purified epoxygeranyl acetate
Result
Result continue
Proton NMR of three products
Proton NMR of crude geraniol with acetylation
Proton NMR of purified geraniol with epoxidation and acetylation
Proton NMR of crude geraniol with epoxidation and acetylation
*Proton NMR of purified geraniol with acetylation
Vanadium-Catalyzed Epoxidation of Allylic alcohol

Kun Yoon
Crude epoxygeranyl acetate
- Useful in organic and commercial synthesis

- VO(acac)2 selectively epoxidate allylic alcohols

- Two experiments
in presence of VO(acac)2
absence of VO(acac)2

- Proton NMR analysis & TLC & Column Chromatography
1
1
Itoh, T.; Jitsukawa, K.; Kaneda, K.; Teranishi, S., American Chemical Society, 1979, 101:1, 159 – 169
----------------------------------------------
With catalyst
Without catalyst
TLC
Retention factor, Rf, values were calculated and compared to determine which aliquots contained desired product (epoxygeranyl acetate)
Order
1.

Preparation of vinyl aromatic-allylic alcohol copolymers

20. Synthesis of primary homoallylic amines by metallacycle-mediated coupling
of TMS-imines (generated in situ) with allylic alcohols.19. Skipped polyenes by chemo-, regio- and stereoselective coupling between
alkynes and 1,5-dienes.18. Skipped trienes via metallacycle-mediated vinylcyclopropane–alkyne
cross-coupling.17. Quinolizidines and indolizidines by metallacycle-mediated allylic alcohol–
imine coupling and aza-Sakurai.16. Exo-alkylidene γ-lactams by imine–allylic alcohol coupling and Pd-catalyzed
carbonylation.15. Piperidines by metallacycle-mediated alkyne–imine cross-coupling and
iminium ion-based cyclization.14. (Z)-homoallylic amines through metallacycle-mediated allylic alcohol–
imine coupling.13. (E)-anti-homoallylic amines through metallacycle-mediated allylic alcohol–
imine coupling.12. A stereochemically complementary process to the Claisen rearrangement:
Stereoselective coupling/oxidation between allylic alcohols and vinylsilanes.11. Metallacycle-mediated coupling between allenes and imines:
Stereoselective synthesis of dienylic amines.10. (Z)-selective synthesis of 1,4-dienes by metallacycle-mediated allylic
alcohol–alkyne cross-coupling.9. (E)-selective synthesis of 1,4-dienes by metallacycle-mediated allylic
alcohol–alkyne cross-coupling.8. 1,5-amino alcohols and piperidines by metallacycle-mediated alkene–imine
cross-coupling.7. Metallacycle-mediated coupling between alkynes and allenes:
Stereoselective synthesis of cross-conjugated trienes.6. Metallacycle-mediated coupling between alkynes and allenes:
Stereoselective synthesis of 1,4-dienes.5. Tetrasubstituted α,β-unsaturated γ-lactams from alkyne–imine coupling.4. First regio- and stereoselective metallacycle-mediated alkene–alkyne
cross-coupling.3. First regioselective cross-coupling between internal alkynes.2. Regioselective alkyne–alkyne cross-coupling for polypropionate assembly.

Carbon chain synthesis by allylic substitution, allylation

The convergent total synthesis of brevetoxin B (1) has been achieved. The intramolecular allylation of the O,S-acetal 20, prepared from the α-chlorosulfide 17 and the alcohol 5, was carried out using AgOTf as a Lewis acid to give the diene 21, predominantly. Ring-closing metathesis of 21 with the Grubbs catalyst 23 afforded the hexacyclic ether 25 which was converted to the A-G ring segment 2 through several steps. The intramolecular allylation of the α-acetoxy ether 42, prepared from 2 and the J-K ring segment 3, followed by ring-closing metathesis provided the polycyclic ether framework 44. A series of reactions of 44, including oxidation of the A ring, deprotection of the silyl ethers, and selective oxidation of the resulting allylic alcohol, furnished 1.

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