Oxygen alkene/alkyne reactions

Like alkynes, a variety of mechanistic motifs are available for the transition metal-mediated etherification of alkenes. These reactions are typically initiated by the attack of an oxygen nucleophile onto an 72-metalloalkene that leads to the formation of a metal species. As described in the preceding section, the G-O bond formation event can be accompanied by a wide range of termination processes, such as fl-H elimination, carbonylation, insertion into another 7r-bond, protonolysis, or reductive elimination, thus giving rise to various ether linkages. 

The Reactions of Diazoacetic Esters with Alkenes, Alkynes, Heterocyclic and Aromatic Compounds V. Dave and E. W. Warnhoff, Org. React., 1970,18, 217-402. Reactions of Singlet Oxygen with Heterocyclic Systems H. H. Wasserman and B. H. Lipshutz, Org. Chem., 1970, 40, 429-509. 

Oxygenation with Ozone Ozone can be depicted as the resonance hybrid of canonical structures 68a-68d and this might explain why in conventional reactions ozone reacts as a 1,3 dipole, either an electrophile or a nucleophile. The electrophilic nature of ozone has been recognized in its reactions toward alkenes, alkynes, arenes, amines, sulfides, phosphines, and Reactions of ozone as a nucleophile, however, are less well... 

Abstract Progress in the field of metal-catalyzed redox-neutral additions of oxygen nucleophiles (water, alcohols, carboxylic acids, and others) to alkenes, alkynes, and allenes between 2001 and 2009 is critically reviewed. Major advances in reaction chemistry include development of chiral Lewis acid catalyzed asymmetric oxa-Michael additions and Lewis-acid catalyzed hydro-alkoxylations of nonacti-vated olefins, as well as further development of Markovnikov-selective cationic gold complex-catalyzed additions of alcohols or water to alkynes and allenes. 

Oxazoles are competent dienes for Diels-Alder reactions with alkenes, alkynes, and singlet oxygen however, the initial cycloadduct is unstable and decomposes to yield different products depending on the nature of the dienophile. 

Alkanes, also known as paraffins (i.e., little affinity), are considered unreactive compared to related alkenes. alkynes. and arenes. Indeed, the n systems in the unsaturated compounds dramatically increase the variety of transformations they can undergo and they serve as the locus for those reactions that is, the alkyl portions of the unsaturated compounds, which are alkane-like, are also relatively unreactive compared to the site of unsaturation. However, all of the hydrocarbons can be oxidized by oxygen, and those with n systems more or less readily undergo reaction with hydrogen to produce alkanes. 

The process of transfer of one hydrogen atom from an allylic alkene (an ene) to an electrophilic alkene (an enophile) followed by formation of a new cr-bond and migration of allylic double bond is known as ene reaction or Alder ene reaction [1]. The ene may be an alkene, alkyne, allene, cyclopropane ring or arene, whereas an enophile may be an alkene, carbonyl, thiocarbonyl, imino or diazo compound having an electron withdrawing substituent. Oxygen may also serve as an enophile. The reaction usually takes place from left to right, since a new [Pg.161]

Methylarsine, trifluoromethylarsine, and bis(trifluoromethyl)arsine [371-74-4] C2HAsF, are gases at room temperature all other primary and secondary arsines are liquids or solids. These compounds are extremely sensitive to oxygen, and ia some cases are spontaneously inflammable ia air (45). They readily undergo addition reactions with alkenes (51), alkynes (52), aldehydes (qv) (53), ketones (qv) (54), isocyanates (55), and a2o compounds (56). They also react with diborane (43) and a variety of other Lewis acids. Alkyl haUdes react with primary and secondary arsiaes to yield quaternary arsenic compounds (57). 

Mascarenas developed a synthetic method to 1,5-oxygen-bridged medium-sized carbocycles through a sequential ruthenium-catalyzed alkyne-alkene coupling and a Lewis-acid-catalyzed Prins-type reaction (Eq. 3.45). The ruthenium-catalyzed reaction can be carried out in aqueous media (DMF/H20 = 10 1).181... 

Though relatively stable,explosions have been caused by distillation to dryness [1], or attempted distillation at ambient pressure [2]. In a comprehensive review of the use of the hydroperoxide as a selective metal-catalysed oxygenator for alkenes and alkynes, attention is drawn to several potential hazards in this application. One specific hazard to be avoided stems from the fact that Lucidol TBHP-70 contains 19% of di-ferf-butyl peroxide which will survive the catalysed reaction and may lead to problems in the work-up and distillation [3], A thorough investigation of the stability and explosive properties of the 70% solution in water has been carried out [4]. The anhydrous peroxide as a solution in toluene may now readily be prepared azeotropically, and the solutions are stable in storage at ambient temperature. This solution is now a preferred method for using the anhydrous hydroperoxide [5],... 

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