Synthetic Reactions with Organozinc Compounds

MISCELLANEOUS SYNTHETIC REACTIONS WITH ORGANOZINC COMPOUNDS 

Reformatsky reagents react with a-amino ethers to give -amino esters (67). Acetals undergo alkoxymethylation of Reformatsky reagents (98). 

There is a competition between alkoxymethylation and acylation in this reaction. Alkoxymethylation by cleavage of acetals is also applicable to alcoholates obtained by condensing Reformatsky reagents with aldehydes and ketones (98, 174a). 

Allylic organozinc compounds react with amino ether and aminothio ether to give unsaturated amines in good yields (96, 329). For example, 

The reactions of a-chloro ethers with phenols and phenol ethers in the presence of zinc afford diarylmethanes. For example, 

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V. Miscellaneous Synthetic Reactions with Organozinc Compounds... 

MISCELLANEOUS SYNTHETIC REACTIONS WITH ORGANOZINC COMPOUNDS... 

Because of the separation of this chapter into fundamental synthetic and structural aspects of organozinc compounds and the applications of these compounds in organic synthesis, many topics are treated twice, but with decidedly different emphases. By way of example, the important organozinc alkoxides are covered first in the inorganometallic section, where the emphasis is on their syntheses, structures, and applications other than in organic synthesis. Later, in Section 2.06.16.2, the uses of such compounds as chiral catalysts in asymmetric addition reactions are discussed. 

Some synthetically important allenylmetallics, such as allenylzinc and allenylin-dium reagents, are prepared from allenylpalladium intermediates. These reactions are discussed in appropriate sections of this chapter. This section covers the reactions of allenylpalladium compounds without further transmetallation. Allenylpalladium complexes can be prepared from propargylic halides, acetates, carbonates, mesylates, alcohols and certain alkynes [83-87], The allenylpalladium compound prepared from 3-chloro-3-methyl-l-butyne has been isolated and characterized spectroscopically (Eq. 9.106) [83], It was found to couple with organozinc chlorides to produce homologated allenes quantitatively (Eq. 9.107). 

A number of transmetalation procedures leading to zinc organometallics can be performed. Many organometallics having a polar C—Met bond are readily transmetalated by the reaction with a zinc salt to the more covalent organozinc compounds. The synthetic... 

The intramolecular Wurtz-type coupling of dihaloorganic compounds with use of metallic zinc is a classical synthetic route to cyclic compounds. For example, cyclopropane derivatives can be prepared from 1,3-dihalo-propanes (29, 189a, 248, 451), and cyclobutane derivatives from 1,4-dihalobutanes (71). These reactions presumably proceed via the intermediate formation of organozinc compounds. The reaction of diethylzinc with esters of a,a -dibrominated aliphatic dicarboxylic acids leads to the... 

Freund 1861. It was PebaFs co-worker Freund [7] who was the first to apply the newly developed organozinc compounds for synthetic purposes in organic chemistry. He prepared several ketones by the reaction of these organometallics with acid chlorides. 

Edward Flankland in Bunsen s laboratory synthesized organozinc compounds by direct reaction of alkyl iodide with zinc in 1849 [18,19]. This synthetic reaction... 

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