Alkene from carbonyls

Hodgson, D. M. Boulton, L. T. Chromium- and Titanium-mediated Synthesis of Alkenes from Carbonyl Compounds. In Preparation of Alkenes-, Williams, J. M. J., Ed. Oxford University Press Oxford, 1996 pp 81-93. 

In 1954, Georg Wittig (then at the University of ThUngen) reported a method of synthesizing alkenes from carbonyl compound, whidi amounts to the replace-... 

The Wittig reaction is often used to form alkenes from carbonyl compounds. In this experiment, the isomeric dienes cis, trans-, and trans, fr ns-l,4-diphenyl-l,3-butadiene will be formed from cinnamaldehyde and benzyltriphenyl-phosphonium chloride. 

Introduction. The Peterson-type olefination reaction has emerged as an extremely useful method for the preparation of alkenes from carbonyl compounds. Synthetically useful vinylsilanes can be prepared by using the Peterson-type olefination reaction of bis(silyl)methylmetal with carbonyl compounds. Among the various reported bis(silyl)methyhnetals, [bis(2-pyri-dyldimethylsilyl)methyl]lithium is an extremely efficient reagent for the stereoselective preparation of vinylsilane. ... 

In Summary Phosphorus ylides add to aldehydes and ketones to give betaines that decompose by forming carbon-carbon double bonds. The Wittig reaction affords a means of synthesizing alkenes from carbonyl compounds and haloaUcanes by way of the corresponding phosphonium salts. 

The synthesis of terminal alkenes from carbonyl compounds is a very important reaction in organic synthesis. Najera and co-workers found out that BTFP methyl sulfone is a good reagent to perform methylation reactions of carbonyl compounds through the Julia-Kocienski protocol. The reaction proved to be much more efficient when Barbier-type conditions were used. Example, alkene 90 was obtained in 45% yield by reacting sulfone 88 with diketone 89 in the presence of P4- -Bu in THF. For example, the sulfone 92, prepared from 84 by two-steps reaction in 81% yield, was converted to alkene 94 in 95% yield and 96 in 71% yield respectively. 

Mychajlowskij, M., and T. H. Chan The synthesis of alkenes from carbonyl compounds and carbanions a to silicon. V. Stereoselective synthesis of E and Z-disubstituted alkenes. Tetrahedron Lett. 1976,4439—4442. 

Unsymmetrical ketones can be made by using either thexylborane or thexylchloroborane.12 Thexylborane works well when one of the desired carbonyl substituents is derived from a moderately hindered alkene. Under these circumstances, a clean monoalkylation of thexylborane can be accomplished, which is then followed by reaction with a second alkene and carbonylation. 

The loss of alkenes from molecular ions of carbonyl compounds has early been noted. [23,82] Soon, a mechanism involving y-H shift and P-cleavage has been proposed and studied in detail. [24-26,83,84] Strictly speaking, the term McLafferty rearrangement only describes an alkene loss from molecular ions of satu-... 

Alkenes from a-silyl carbanion and carbonyl compounds. Also known as sila-Wittig reaction. 

Alcohols may be prepared (1) by hydration of alkenes (1) in presence of an acid and (11) by hydroboratlon-oxidatlon reaction (2) from carbonyl compounds by (1) catalytic reduction and (11) the action of Grignard reagents. Phenols may be prepared by (1) substitution of (1) halogen atom In haloarenes and (11) sulphonic acid group In aiyl sulphonic acids, by -OH group (2) by hydrolysis of diazonium salts and (3) industrially from cumene. 

Isomeric polymers can also be obtained from a single monomer if there is more than one polymerization route. The head-to-head placement that can occur in the polymerization of a vinyl monomer is isomeric with the normal head-to-tail placement (see structures III and IV in Sec. 3-2a). Isomerization during carbocation polymerization is another instance whereby isomeric structures can be formed (Sec. 5-2b). Monomers with two polymerizable groups can yield isomeric polymers if one or the other of the two alternate polymerization routes is favored. Examples of this type of isomerism are the 1,2- and 1,4-polymers from 1,3-dienes (Secs. 3-14f and 8-10), the separate polymerizations of the alkene and carbonyl double bonds in ketene and acrolein (Sec. 5-7a), and the synthesis of linear or cyclized polymers from non-conjugated dienes (Sec. 6-6b). The different examples of constitutional isomerism are important to note from the practical viewpoint, since the isomeric polymers usually differ considerably in their properties. 

Using the catalyst system described above in combination with a rhodium phosphine catalyst Lebel reported the de novo synthesis of alkenes from alcohols [100]. They developed a one-pot process, avoiding the isolation and purification of the potentially instable aldehyde intermediate. They combined the oxidation of alcohols developed by Sigman [89] with their rhodium-catalyzed methylenation of carbonyl derivatives. The cascade process is compatible with primary and secondary aliphatic as well as benzyUc alcohols in good yields. They even added another reaction catalyzed by a NHC complex, the metathesis reaction, which has not been addressed in this review as there are many good reviews, which exclusively and in great depth describe all aspects of the reaction. 

Functionalized zinc carbenoids have been prepared from carbonyl compounds by an indirect strategy. The deoxygenation of a carbonyl compound to an organozinc carbenoid can be induced by a reaction with zinc and TMSCl. Therefore, the aldehyde or ketone, when treated with TMSCl or l,2-bis(chlorodimethylsilyl)ethane in the presence of an alkene, generates the cyclopropanation product. This method is quite effective for the production of alkoxy-substituted cyclopropane derivatives. A 55% yield of the... 

Dihydroisoxazoles with a substituent at nitrogen are most conveniently prepared by 1,3-dipolar cycloaddition of nitrones to alkenes or alkynes. Nitrones are usually prepared in situ from carbonyl compounds and /V-(alkyl)hydroxylamines (Figure 15.10). 

Epoxides (see also a,(3-Epoxy alcohols, etc., Glycidic acids, esters, nitriles) From alkenes by epoxidation Dimethyldioxirane, 120 Fluorine-Acetonitrile, 135 Potassium peroxomonosulfate, 259 From carbonyl compounds Alumina, 14... 

On the pages which follow, general methods are illustrated for the synthesis of a wide variety of classes of organic compounds including acyl isocyanates (from amides and oxalyl chloride p. 16), epoxides (from reductive coupling of aromatic aldehydes by hexamethylphosphorous triamide p. 31), a-fluoro acids (from 1-alkenes p. 37), 0-lactams (from olefins and chlorosulfonyl isocyanate p. 51), 1 y3,5-triketones (from dianions of 1,3-diketones and esters p. 57), sulfinate esters (from disulfides, alcohols, and lead tetraacetate p. 62), carboxylic acids (from carbonylation of alcohols or olefins via carbonium-ion intermediates p. 72), sulfoxides (from sulfides and sodium periodate p. 78), carbazoles... 

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