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Carbonyl Olefination Utilizing Metal Carbene Complexes

Carbonyl Olefination Utilizing Metal Carbene Complexes [Pg.151]

The Wittig-type olefination of carbonyl compounds is one of the characteristic reactions of carbene complexes. High-valent carbene complexes of early transition metals show ylide-like reactivity to vards carbonyl compounds. In 1976, Schrock first demonstrated that niobium and tantalum neopentylidene complexes 1 and 2, the typical nucleophilic Schrock-type carbene complexes, olefinate various carbonyl compounds including carboxylic acid derivatives [4]. [Pg.151]

Carbonyl Olefination with Titanocene-Methylidene and Related Reagents [Pg.152]


Takeda, T., Tsubouchi, A. Carbonyl Olefination Utilizing Metal Carbene Complexes in Modern Carbonyl Olefination" Ed. Takeda, T., Wiley-VCH Weinheim, 2004, Chapter 4, p 151-199. [Pg.393]

Carbonyl Olefination Utilizing Metal Carbene Complexes... [Pg.151]

Scheme 4.2. Carbonyl olefination utilizing metal-carbene complexes. Scheme 4.2. Carbonyl olefination utilizing metal-carbene complexes.
I 4 Carbonyl Olefination Utilizing Metal Carbene Complexes Tab. 4.1. Methylenation of ketones with the Tebbe reagent 3. [Pg.154]

The mechanisms of these reactions bear marked similarities, in spite of the differences in their reactivities and selectivities. Thus, in certain cases, a four-membered intermediate similar to the 1,2-oxaphosphetane intermediate in the Wittig reaction appears in the Peterson reaction as a pentacoordinate 1,2-oxasiletanide. Reactions of transition metal carbene complexes with carbonyl compounds also proceed through the formation of a four-membered oxametallacycle, which was recently found to be an intermediate of some McMurry reactions. Carbonyl olefination utilizing dimetallic species of zinc or chromium is somewhat similar to the Julia reaction in that they both involve the process of ) -elimination. [Pg.364]

Schrock-type carbene complexes of transition metals other than titanium are also utilized for carbonyl olefination, although their synthetic utility has not yet been fully investigated. In some cases, their reactions differ from those of titanium-carbene complexes in terms of stereo- and chemoselectivity and are complementary to olefination with titanium reagents. This section describes the use of carbene complexes of various transition metals in carbonyl olefination. [Pg.185]


See other pages where Carbonyl Olefination Utilizing Metal Carbene Complexes is mentioned: [Pg.180]    [Pg.159]    [Pg.180]    [Pg.159]    [Pg.185]    [Pg.188]    [Pg.195]    [Pg.43]    [Pg.159]    [Pg.37]    [Pg.159]   


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Carbene complexes metal carbonyls

Carbene-olefin

Carbene-olefin metal complex

Carbenes metal carbene complex

Carbenes metal complexes

Carbonyl olefination

Complexes metal carbene

Metal carbenes

Metal carbonyl complexes

Olefin complexation

Olefin complexes

Olefin-metal complexes

Olefines, complexes

Olefins carbonylation

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