Chloromethyl epoxides

Epoxides bearing a leaving group in a suitable position, such as chloromethyl epoxides, react with sodium telluride (prepared by the Rongalite method), giving allyhc alcohols. ... 

The epoxidation is generally conducted in two steps (/) the polyol is added to epichlorohydrin in the presence of a Lewis acid catalyst (stannic chloride, boron triduoride) to produce the chlorohydrin intermediate, and (2) the intermediate is dehydrohalogenated with sodium hydroxide to yield the aliphatic glycidyl ether. A prominent side-reaction is the conversion of aliphatic hydroxyl groups (formed by the initial reaction) into chloromethyl groups by epichlorohydrin. The aliphatic glycidyl ether resins are used as flexibilizers for aromatic resins and as reactive diluents to reduce viscosities in resin systems. 

Reaction of the carbanion of chloromethyl phenyl sulphoxide 409 with carbonyl compounds yields the corresponding 0-hydroxy adducts 410 in 68-79% yield. Each of these compounds appears to be a single isomer (equation 242). Treatment of adducts 410 with dilute potassium hydroxide in methanol at room temperature gives the epoxy sulphoxides 411 (equation 243). The ease of this intramolecular displacement of chloride ion contrasts with a great difficulty in displacing chloride ion from chloromethyl phenyl sulphoxide by external nucleophiles . When chloromethyl methyl sulphoxide 412 is reacted with unsymmetrical ketones in the presence of potassium tcrt-butoxide in tert-butanol oxiranes are directly formed as a mixture of diastereoisomers (equation 244). a-Sulphinyl epoxides 413 rearrange to a-sulphinyl aldehydes 414 or ketones, which can be transformed by elimination of sulphenic acid into a, 8-unsaturated aldehydes or ketones (equation 245). The lithium salts (410a) of a-chloro-/ -hydroxyalkyl... 

A versatile method for the synthesis of perhydrofuropyrans begins with 2-chloromethyl-3-(2-methoxyethoxy)pro-pene, 79. Compound 79, in the presence of lithium powder and a catalytic amount of naphthalene, undergoes sequential reaction with two electrophiles, first a carbonyl compound and then an epoxide, to form methylidenic diols. Hydroboration-oxidation, followed by oxidation with PCC, affords perhydrofuropyrans (Scheme 15) <2000TL1661, 2001SL1197, 2003T5199>. 

Analogously, (/ )-(—)-chloromethyl p-tolyl sulfoxide has been prepared with 97% e.e. and used for the enantioselective synthesis of epoxides [394],... 

The epoxidation of the carbon-carbon double bond in ethyl 3-methyleneazetidine-l-carboxylate 46 using w-chloroperbenzoic acid and the regioselective ring opening of the resulting epoxide 47 with HBr and HC1 led to the synthesis of ethyl 3-bromomethyl-3-hydroxyazetidine-l-carboxylate 48 and ethyl 3-chloromethyl-3-hydroxyaze-tidine-l-carboxylate 49, respectively (Scheme 8) <1997JOC4434>. 

Peptide aldehydes constitute a rather general example of protease inhibitors. The electrophilic carbonyl group is attacked reversibly by the cleaving nucleophile, forming a covalent acetal or thioacetal intermediate. With cysteine proteases the preferred inhibitors are strong electrophiles, for example ketones, chloromethyl ketones, epoxides, or vinyl sulfones. Many cysteine protease inhibitors form an enzyme-inhibitor complex irreversibly these are therefore denoted suicide-inhibitors . 

Triazoles and tetrazoles can be alkylated on nitrogen under basic conditions, as in the synthesis of the clinically-used antifungal drug 8.35 in which 11,2,4-triazole is alkylated by a chloromethyl ketone and an epoxide, both good alkylating agents. What is the mechanism of formation of epoxide 8.34 Of compounds 8.34 and 8.35, which is achiral and which is racemic ... 

Amino-6-chloromethyl- (248) gave 3-amino-6-butoxymethyl-2-pyrazinecar-bonitrile (249) (BuOH, reflux, 12 days 77% or likewise, 2 days 58%).612 Also other examples 53,391,871,957 1059,1139 for examples of intramolecular alcoholysis (epoxide formation) see end of this section. 

Reactions of salicylic aldehydes with the chloromethyl tolyl sulfone anion afford 2-hydroxydihydrobenzofurans in moderate to good yields (Scheme 98) <1998T6811>. Formation of an epoxide intermediate that rearranges to the corresponding homologated alcohol is believed to be involved. Decarboxylation of the reaction product is prevented by lactol formation <1998T6811>. 

The outcome of the action of sulfur tetrafluoride on epoxides mainly depends on the substituents present on the epoxide ring. 1-Aryl-, 1,1-diaryl- and 1,1-dialkyloxiranes give rearranged geminal difluorides in low to moderate yield. From 1,2-diaryloxiranes, (chloromethyl)oxi-... 

Figure 2.1. Brevetoxins are based on two different structural backbones, based on what are perceived to be the two parent molecules, PbTx-2 (brevetoxin B) and PbTx-1 (brevetoxin A). All other known derivatives are based on alteration of the R-side chain, epoxidation across the double bond in the H-ring of PbTx-2, or derivatization at the C-37 hydroxyl in PbTx-2. PbTx-8, the chloromethyl ketone derivative of PbTx-2, is an artifact of chloroform extraction and subsequent phosgene conversion of PbTx-2. Common features include trans-fused polyether ring systems consisting of five- to nine-membered rings. denotes likely chemical artifact from extraction (Baden et al. 2005).

Neutral a-alkyliron complexes are obtained upon reaction of Na[Cp(CO)2pe] (5) with alkyl halides (9) (Scheme 6), and as with Collman s reagent this occurs in an Sn2 fashion with inversion of coirfiguration at the carbon atom. Epoxides also participate in this reaction, but tertiary alkyl halides are poor substrates. Alternatively, complexes (9) may be prepared by reaction of an appropriate metal alkyl with Cp(CO)2PeX (6). Typically complexes of this type are prepared in order to gain access to the synthetically nseful cationic rf--alkene iron complexes (Section 4.1.2). Also, nucleophilic addition of (5) to heteroatom-snbstituted alkyl halides (snch as methoxymethylchloride or chloromethyl methyl snllide) affords complexes of type (9) that can be converted to cationic... 

One scheme for preparing a key intermediate for incorporating that fragment begins with the chloromethyl ketone (1) derived from phenylalanine, in which the amine is protected as a carbobenzyloxy (Cbz) group. Reduction of the carbonyl group by means of borohydride affords a mixture of aminoalcohols. The major syn isomer 2 is then isolated. Treatment of 2 with base leads to internal displacement of halogen and formation of the epoxide (3). ... 

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