Alkylation of epoxides

Abe, N. Hanawa, H. Maruoka, K. Sasaki, M. Miyashita, M. Highly effident alkylation of epoxides with R3A1/H20 systems based on the double activation of epoxy oxygens. Tetrahedron Lett. 1999, 40, 5369-5372. 

Mukerji et al. has reported the regioselective alkylation of epoxides with the ate reagent MeLi/Ln(btsa)3 (Eq. 26) [290]. The stereoselectivity of the alkylation reaction of styrene oxide and butadienoxide is complementary to that of organocopper reagents. 

A highly effective catalytic method for alkynylation of epoxides has recently been reported this involves the chelation-controlled alkylation of hetero-substituted epoxides with Mc3A1 and alkynyllithiums via pentacoordinate organoaluminum complexes [82]. For instance, reaction of epoxy ether, (l-benzyloxy)-3-butene oxide (75) in toluene with PhC = CLi under the influence of catalytic MesAl (10 mol%) proceeded smoothly at 0 °C for 5 h to furnish the alkynylation product l-(benzyloxy)-6-phenylhex-5-yn-3-ol (76) in 76 % yield. The yield of the product was very low (3 %) without MeaAl as catalyst under similar conditions. This is the first catalytic procedure for amphiphilic alkylation of epoxides. The participation of pentacoordinate MesAl complexes of epoxy ethers of type 75 is emphasized by comparing the reactivity with the corresponding simple epoxide, 5-phenyl-l-pentene oxide (77), which was not susceptible to nucleophilic attack of PhC s CLi with catalytic Me3Al under similar conditions (Sch. 50). 

Lithium enolates of ketones, esters, and amides do not react directly with epoxides but require a promoter such as EtjAlCl, LiC104, or LiCl. However, alkylations of epoxides do occur with Li[CH2C02C(CH3)3], Na[HC(C02Et)2], Li[CR2C02Li], or Li[CR2C02Na]. 9... 

Intramolecular alkylations of epoxides at rp -centers are also possible thus treatment of the epoxyamide (173) with i-butyllithium affords moderate to good yields of the dihydiobenzofurans (174). However, the homologous system (175) is converted into the tetralin framework (176) rather than to an indan derivative, with the magnesium bromide presumably serving to activate the epoxide. Under similar conditions, the styrene oxide (177) is converted into the benzocyclobutanol (178) presumably by... 

Lanthanoid Complexes as Reagents in Organic Synthesis. Alkylations of Epoxides... 

Alkylation of Enolates (condensation of enolates with alkyl halides and epoxides) Comprehensive Organic Synthesis 1991, vol. 3, 1. 

As shown m Table 6 4 electron releasing alkyl groups on the double bond increase the rate of epoxidation This suggests that the peroxy acid acts as an electrophilic reagent toward the alkene... 

The use of epoxides as alkylating agents for diethyl malonate provides a useful route to y lactones Wnte equations illustrating such a sequence for styrene oxide as the starting epoxide Is the lactone formed by this reaction 3 phenylbutanohde or is it 4 phenylbutanohde ... 

Another type of soHd supetacid is based on perfluorinated resin sulfonic acid such as the acid form of Du Font s Nafion resin, a copolymer of a perfluorinated epoxide and vinylsulfonic acid or soHd, high molecular weight petfluotoalkanesulfonic acids such as petfluotodecanesulfonic acid, CF2(CF2)qS02H. Such sohd catalysts have been found efficient in many alkylations of aromatic hydrocarbons (225) and other Friedel-Crafts reactions (226). 

Epo>y Compounds. Epoxidized soya oil (ESO) is the most widely used epoxy-type additive and is found ia most mixed metal stabilized PVC formulations at 1.0—3.0 phr due to its versatiHty and cost effectiveness. Other usefiil epoxy compounds are epoxidized glycerol monooleate, epoxidized linseed oil, and alkyl esters of epoxidized tall oil fatty acid. 

Additioaal uses for higher olefias iaclude the productioa of epoxides for subsequeat coaversioa iato surface-active ageats, alkylatioa of benzene to produce drag-flow reducers, alkylation of phenol to produce antioxidants, oligomeriza tion to produce synthetic waxes (qv), and the production of linear mercaptans for use in agricultural chemicals and polymer stabilizers. Aluminum alkyls can be produced from a-olefias either by direct hydroalumination or by transalkylation. In addition, a number of heavy olefin streams and olefin or paraffin streams have been sulfated or sulfonated and used in the leather (qv) iadustry. 

Induction of Asymmetry by Amino Acids. No fewer than sis types of reactions can be carried out with yields of 75—100% usiag amino acid catalysts, ie, catalytic hydrogenation, iatramolecular aldol cyclizations, cyanhydrin synthesis, alkylation of carbonyl compounds, hydrosdylation, and epoxidations (91). 

Alkylation of enamines with epoxides or acetoxybromoalkanes provided intermediates for cyclic enol ethers (668) and branched chain sugars were obtained by enamine alkylation (669). Sodium enolates of vinylogous amides underwent carbon and nitrogen methylation (570), while vicinal endiamines formed bis-quaternary amonium salts (647). Reactions of enamines with a cyclopropenyl cation gave alkylated imonium products (57/), and 2-benzylidene-3-methylbenzothiazoline was shown to undergo enamine alkylation and acylation (572). A cyclic enamine was alkylated with methylbromoacetate and the product reduced with sodium borohydride to the key intermediate in a synthesis of the quebrachamine skeleton (57i). 

Variations and Improvements on Alkylations of Chiral OxazoUnes Metalated chiral oxazolines can be trapped with a variety of different electrophiles including alkyl halides, aldehydes,and epoxides to afford useful products. For example, treatment of oxazoline 20 with -BuLi followed by addition of ethylene oxide and chlorotrimethylsilane yields silyl ether 21. A second metalation/alkylation followed by acidic hydrolysis provides chiral lactone 22 in 54% yield and 86% ee. A similar... 

Alkylation of orgatiomatigatiese reagaits witli alkyl bromides can also be improved by adrlition of CuCl f3 mol96). Hie reactions proceed at room temperature and are complete witliin a few bouts [123, 130], Hie opening of epoxides is also improved under tliese conditions. Hie reaction also features good clienioselectivity, tolerating tlie presence of sensitive functions sucli as ketones t Sclieme 2.59) [130]. 

Hie same autliors also studied tlie alkylation of alkynyl epoxides for fornialion of optically active a-aUenic alcohols under kinetic resolution ctmdilions fSdieme 8.29) [54]. 

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