Ethers with organometallic

Cleavage of amine ethers with organometallic compounds... 

Silicon-based Lewis acids have been known for some time, and the related chemistry in catalysis has recently been reviewed [24]. Most examples in the literature are mainly based on achiral species and will be discussed only briefly in this section. In general, a broad variety of reactions can be catalyzed with compounds like MejSiOTf, MejSiNTf or MOjSiClO. One advantage over some metal Lewis acids is that they are compatible with many carbon nucleophiles like silyl enol ethers, allyl organometallic reagents and cuprates. 

Fluoral hydrate and hemiacetals are industrial products. They are stable liquids that are easy to handle, and they react as fluoral itself in many reactions. Thus, in the presence of Lewis acids, they react in Friedel-Crafts reactions. They also react very well with organometallics (indium and zinc derivatives) and with silyl enol ethers.Proline-catalyzed direct asymmetric aldol reaction of fluoral ethyl hemiac-etal with ketones produced jS-hydroxy-jS-trifluoromethylated ketones with good to excellent diastereo- (up to 96% de) and enantioselectivities. With imine reagents, the reaction proceeds without Lewis acid activation. The use of chiral imines affords the corresponding 8-hydroxy ketones with a 60-80% de (Figure 2.49). ° ... 

Cleavage of amine ethers with or-ganometallic compounds 0-93 Reaction of organometallic compounds with aziridines 0-97 Alkylation of amines... 

Addition to quinone monoketals and quinol ethers.2 Complexation of quinone monoketals or quinol ethers with MAD permits 1,4-addition of organo-lithium and Grignard reagents. Highest yields obtain with aryl, vinyl, and acetylenic organometallics. 

Just about the same time Japanese workers (107) polymerized this dialdehyde with boron trifluoride etherate, p-toluene sulfonic acid, and titanium tetrachloride as well as with aluminum triethyl-water catalyst systems. Completely insoluble products were obtained with the cationic catalysts, whereas partially soluble materials were isolated with the latter initiator. On the basis of infrared evidence, the above structure was assigned to the soluble product. In spite of the fact that ether linkages were found by infrared analysis in the cationic product, the authors concluded that its structure was different from that of the soluble polymer obtained with organometallic catalyst. The structure of the soluble fraction was assumed to be ... 

To have more insight into the reaction mechanism and the stereochemical outcome of the reaction, the following two experiments were performed. First, it was checked that the reaction of trisubstituted enol ether with two alkyl groups, such as 114, did not lead to the vinylic organometallic derivative [63] (Scheme 41), indicating that this tandem reaction should occur first by the isomerization of the remote double bond (only in the case of 98i, the direct transformation of methoxy-enol ether into an organometallic derivative was... 

Hydroxypropylatiott Reaction of(l) in ether with lithium wire(l %sodium)alO° gives the organometallic reagent (2), which is a satisfactory carrier of the hydroxypropyl group. Thus (2) reacts with cyclohexanone in ether to give the adduct (3) in 90% yield. 

By reaction of nickel acetylacetonate with organometallic compounds in ether in the presence of all-fran -cyclodecatriene, we obtained an intensely red solution from which dark red crystals could be isolated. These are volatile under high vacuum and have the composition NiCi2Hi8- The mass spectrum shows the molecule to have peaks at 220 and 222. This is in agreement with NiCi2Hi8, if we consider that nickel consists of the isotopes Ni and Ni . The infrared spectrum shows that all double bonds are shared with nickel, because there is no absorption corresponding to normal trans double bonds. 

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