Allylic alkenes

A modern variant is the intramolecular magnesium-ene reaction, e.g. the reaction of the alkene-allylic-Grignard compound 9 to give the five-membered ring product 10. This reaction proceeds regio- and stereoselectively, and is a key step in a synthesis of the sesquiterpenoid 6-protoilludene ... [Pg.105]

Preparing Alkyl Halides from Alkenes Allylic Bromination 339... [Pg.339]

There are several reagents that lead to isomerization of a double bond to form a new alkene. Allyl decyl ether (CH2=CHCH20CioH2i) was isomerized to 1-decyloxy-l-propene (CH3CH=CHOCioH2i) by treatment with NaHFe(CO)4. Many of these reactions were discussed in 12-2. [Pg.991]

The extensive organometallic chemistry of chromium, i.e. the hexacarbonyl and its derivatives, organochromium compounds without carbonyl ligands, cyanide and isocyanide complexes, alkene, allyl, diene, cyclopentadiene and arene derivatives, and complexes of a-donor carbon ligands, has been recorded in Chapters 26.1 and 26.2 of Volume 3 of Comprehensive Organometallic Chemistry .1 In the present section, chromium complexes... [Pg.702]

The reactivity of -Tr-allylpalladium-phosphine complexes generated stoichiometrically or from alkenes allylically substituted with a leaving group, is essentially identical and, as a result, allyl species will be generally considered in this section without distinction as to the origin of the palladium complex. [Pg.590]

Sulfur nucleophiles have not been widely used in ir-allylpalladium chemistry, principally due to their ability to interfere with the catalyst by coordination. This is a less serious concern for sulfinic acid and sulfinate salts than with sulfides, and as a result, several reports have appeared using RSO2H and RSO2-.211-219 Alkenes allylically functionalized with a leaving group, dienes214 and vinyl nitro con-pounds218 219 have all served as precursors for the required ir-allyl species in these reactions (equations 60 and 61). [Pg.599]

In contrast with unreactive, unfunctionalised terminal alkenes, allylic and homoallylic ethers (22, 24) and alcohols (20) from which the product organolithiums (21, 23, 25) can be chelated in a (preferably) five-membered, oxygen-containing ring, carbolithiate rapidly and cleanly.23 Coordination overrides any preference for the lithium to be bonded to the primary carbon, but cannot overcome the unfavourability of forming a tertiary organolithium - 26 gives 27, but 28 cannot be carbolithiated. Coordination to sulfur in similar thioethers 29 works too. [Pg.276]

Chloriuatton of alkenes, Allylic chlorination is usually conducted by a free-radical reaction with NCS. Chlorination can be effected with catalysis by C6H5SeCl, in which case the main product is usually the rearranged allylic chloride. However, the formation of rearranged allylic chloride is sensitive to the structure of the alkenes and also to the particular selenium compound used as catalyst. See also N-phenylselenosuccinimide, this volume. [Pg.362]

On the other hand, the pure (Z)-isomer of 1 on treatment with sec-butyllithium in THF generates the more susbstituted vinyllithium reagent 3. Thus by use of either sequence stereoselective routes are possible to alkenes, allylic aldbhols, and aldehydes. ... [Pg.550]

The reaction of alkenes with iodosobenzene in acetic acid in the presence of sodium azide offers a simple and high yield route to 1,2-diazides (Table 3)76. a-Azido ketones are side products or the exclusive product from the reaction with conjugated alkenes. Allylic azides or oxonitriles, resulting from oxidative cleavage of the C-C double bond, are alternatively obtained from trisubstituted steroid alkenes77. [Pg.709]

D. (T-Carbene, Ciirbyne/7r-Alkene, Allyl. and Alkyne Complexes. . . 266... [Pg.219]

Alkenyllithiums generated from trisylhydrazones react with electrophiles such as primary alkyl bromides, aldehydes, ketones, dimethylformamide, CO2, chloro-trimethylsilane, or 1,2-dibromoethane to furnish substituted alkenes, allylic alcohols, a,(3-unsaturated aldehydes, a,P-unsaturated acids, alkenylsilanes, or alkenyl bromides, respectively, as exemplified below for the preparation of an allylic alcohol and an a,P-unsaturated aldehyde. ... [Pg.389]

THA4(Cr0)PWu039 THA,5(Cr0)SiW11039 Alkene Alkene Allylic alcohol Triphenylphosphine Epoxide, allylic alcohol, allylic ketone Epoxide, allylic alcohol, allylic ketone Allylic ketone Triphenylphosphine oxide MeCN or C6H6 MeCN or C6H6 MeCN c6h6 ... [Pg.718]

Into Alkenes, Allyl Alcohols, and a,P-Unsaturated Ketones (Decyanation Reaction)... [Pg.15]

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