Carbon monoxide with epoxides

Oxymethylation of epoxides. " The reaction of a hydrosilane and carbon monoxide with an epoxide catalyzed by CojfCO), results in a regio- and stereoselective ring opening to give disilyl ethers of a 1,3-diol in generally high yield. 

The insertion reaction of carbon monoxide into epoxides affords -lactones in excellent yields. For example, several epoxides 59 react with carbon monoxide in the presence of porphyrine catalysts to give the j8-lactones 60 stereoselectively, usually in >99 % yield... 

Episulfides can be converted to alkenes. " However, in this case the elimination is syn, so the mechanism cannot be the same as that for conversion of epoxides. The phosphite attacks sulfur rather than carbon. Among other reagents that convert episulfides to alkenes are Bu3SnH, certain rhodium complexes, LiAlH4 (this compound behaves quite differently with epoxides, see 10-85), and methyl iodide.Episulfoxides can be converted to alkenes and sulfur monoxide... 

Copolymerization of Epoxides and Aziridines with Carbon Monoxide... 

Two molecules of carbon monoxide were successively incorporated into an epoxide in the presence of a cobalt catalyst and a phase transfer agent [29]. When styrene oxide was treated with carbon monoxide (0.1 MPa), excess methyl iodide, NaOH (0.50 M), and catalytic amounts of Co2(CO)8 and hexadecyltrimethylammonium bromide in benzene, 3-hydroxy-4-phenyl-2(5H)-furanone was produced in 65% yield (Scheme 7). A possible reaction mechanism was proposed as shown in Scheme 8 Addition of an in situ... 

The elution profile of cytochrome P-448 (absorption at 418 nm) and epoxide hydratase activity from a sodium cholate-solubi-lized hepatic microsomal preparation (from DBA-treated male skates) applied to a DEAE-cellulose column and eluted with Buffer II is shown in Fig. 3. The void volume of the column contained significant amounts of epoxide hydratase activity. Fractions 40-70 (Fig. 3) were combined, and concentrated. The carbon monoxide difference spectrum, which had an absorption maximum at 448 nm in the induced state, is shown in Fig. 4. This form of the cytochrome (i.e.,... 

When all of the material absorbing at 418 nm (associated with the cytochrome P-448 fractions) was eluted from the DEAE-cellulose column (which in some experiments required more than 1 liter of Buffer II), elution was continued with a linear KC1 gradient (0-0.5 M) in Buffer II, as shown in Fig. 5. A different form(s) of cytochrome P-450 (fractions 130-155), having maximal absorption near 451 nm in the carbon monoxide ligated and reduced form (Fig. 6), was obtained although only 2- to 3-fold purification, relative to microsomes, was achieved. This form of cytochrome P-450 was extensively contaminated with epoxide hydratase activity. However, by combining fractions 130-150 (Fig. 5), it was possible to obtain cytochrome P-451 essentially free of cytochrome b5. The relative content of cytochrome P-448 and cytochrome P-451 Tn the DEAE-column eluates ranged from 1 1.1 to 1 1.6 in several different experiments. 

In the reactions of styrene oxide and butadiene monoxide with ester carbanions, attack takes place at both primary and secondary epoxy carbon atoms.The findings provide evidence for the participation of the conjugative effect in the ring opening of these epoxides. 

This enzyme [EC 1.14.13.25] catalyzes the reaction of methane with NAD(P)H and dioxygen to produce methanol, NAD(P), and water. This enzyme is reported to exhibit a broad specificity. Many alkanes can be hydrox-ylated and alkenes are converted into the corresponding epoxides. Carbon monoxide is oxidized to carbon dioxide, ammonia is oxidized to hydroxylamine, and some aromatic compounds and cyclic alkanes can also be hy-droxylated, albeit not as efficiently. 

Deprotonation of complex 1 with butyllithium at — 78 °C generates the enolate species 2 (described in Section 1.1.1.3.4.1.1.), which reacts with electrophiles while in the anti conformation (acyl oxygen anti to carbon monoxide oxygen). Enolate 2 is inert to 1,2-epoxypropane (3a) at — 78 °C, but in the presence of a Lewis acid, rapid reaction ensues leading to preferred alkylation of the least hindered site of the epoxide13. Reaction of the enolate 2, derived from the racemic complex 1, with racemic monosubstituted epoxides results in preferential formation of one of two possible diastereomers this can be termed a double enantiomer-differentiating reaction. 

The mechanism most consistent with all the data is an ionic acid opening of the epoxide —apparently where the hydrocarbonyl is used as an acid to attack the epoxide— which is more sensitive to steric effects than to electronic factors. This conclusion may at first appear to be inconsistent with our previous finding that isobutylene reacted with cobalt hydrocarbonyl to give exclusively addition of the cobalt to the tertiary position. The inhibitory effect of carbon monoxide on that reaction, however, indicated that it was probably cobalt hydrotricarbonyl that was actually adding to the olefin and steric effects would be expected to be much less important with the tricarbonyl than with the tetracarbonyl (7) Apparently he feels now that the former reactions really involve the tricarbonyl, loss of CO being important to get the reaction running whereas epoxide attack perhaps involves a tetracarbonyl, steric factors are more important here. 

The recent dramatic increase in the price of petroleum feedstocks has made the search for high selectivities more urgent. Several new processes based on carbon monoxide sources are currently competing with older oxidation processes.103,104 The more straightforward synthesis of acetic acid from methanol carbonylation (Monsanto process) has made the Wacker process obsolete for the manufacture of acetaldehyde, which used to be one of the main acetic acid precursors. Several new methods for the synthesis of ethylene glycol have also recently emerged and will compete with the epoxidation of ethylene, which is not sufficiently selective. The direct synthesis of ethylene... 

Cationic t 3-allyltetracarbonyliron complexes are generated by oxidative addition of allyl iodide to pentacarbonyliron followed by removal of the iodide ligand with AgBF4 under a carbon monoxide atmosphere [35]. Similarly, photolysis of vinyl epoxides or cyclic vinyl sulfites with pentacarbonyliron or nonacarbonyldiiron provides Jt-allyltricarbonyliron lactone complexes. Oxidation with CAN provides by demetallation with concomitant coupling of the iron acyl carbon to one of the termini of the coordinated allyl moiety either [3- or 8-lactones (Scheme 1.12) [36, 37]. In a related procedure, the corresponding Jt-allyltricarbonyliron lactam complexes lead to P- and 8-lactams [37]. 

A ruthenium-promoted carbonylation of allenyl alcohols 884 is a powerful method for the synthesis of 5,6-dihydropyran-2-ones 885 (Equation 356) <20000L441, 2003JOC8571>. Co2(CO)6-mediated tandem [5+1]/ [2+2+1] cycloaddition reactions of the epoxide 886 with carbon monoxide provide a one-pot synthesis of tricyclic 5,6-dihydropyran-2-ones 887 in good yield (Equation 357) <2003JA9610>. 

The epoxidase catalyzing the 10,11-epoxidation of methyl farnesoate in homogenates of corpora allata from Locusta miqratoria has been studied in detail and has been shown to be a cytochrome P-450-mediated monooxygenase associated with the microsomal fraction. The enzyme is strictly dependent on NADPH and requires oxygen (36). It is sensitive to inhibition by carbon monoxide (36) and to offier compounds such as methyl enedioxyphenyl compounds and imidazoles that are well established inhibitors of the cytochrome P-450-mediated monooxygenases involved in xenobiotic metabolism (37-39). 

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