Allenes additions

Halogenation of alkenyl organometallic compounds Addition of hydrogen halides to triple bonds Halogenation of alkynes or allenes Addition of alkyl halides to triple bonds Addition of acyl halides to triple bonds... 

T. F. Rutledge, Acetylenes and Allenes, Addition, Cyclization and Polymerization. Reinhold, New York, 1969. 

Bis(phosphoranimine) ligands, chromium complexes, 5, 359 Bis(pinacolato)diboranes activated alkene additions, 10, 731—732 for alkyl group functionalization, 10, 110 alkyne additions, 10, 728 allene additions, 10, 730 carbenoid additions, 10, 733 diazoalkane additions, 10, 733 imine additions, 10, 733 methylenecyclopropane additions, 10, 733 Bisporphyrins, in organometallic synthesis, 1, 71 Bis(pyrazol-l-yl)borane acetyl complexes, with iron, 6, 88 Bis(pyrazolyl)borates, in platinum(II) complexes, 8, 503 Bispyrazolyl-methane rhodium complex, preparation, 7, 185 Bis(pyrazolyl)methanes, in platinum(II) complexes, 8, 503 Bis(3-pyrazolyl)nickel complexes, preparation, 8, 80-81 Bis(2-pyridyl)amines... 

These new developments place allene-olefin and allene-allene thermal cycloadditions in a new context framed by the questions Are there reactive intermediates separating reactants and products in the cycloadditions, or in the degenerate rearrangements Might there be a common reactive intermediate for the allene-olefin addition and the methyl-enecyclobutane rearrangement, and another for the allene-allene addition and the 1,2-dimethylenecyclobutane rearrangement How may the experimentally observed stereochemical features of these four processes be reconciled with orbital symmetry theory ... 

Most often in these reactions, however, the monoadduct is isolated and used to prepare the alkylidenecyclopropane, as in the case of the 1 1 allene-2-diazopropane adduct, which on thermolysis generated the singlet trimethylenemethane diradical 59, which closed to give a mixture of l,l-dimethyl-2-methylenecyclopropane (60) and isopropylidenecyclopropane (61). Although a wide variety of alkylidenecyclopropanes have been made in this way (see Table 2), the involvement of trimethylenemethane intermediates in the deazetization step means that mixtures of isomers are normally produced. Attempted syntheses of alkylidenecyclopropanes by this route have sometimes been frustrated by tautomerism and autoxidation of the intermediate 4,5-dihydro-3i/-pyrazole or by a reversal in the regiochemistry of the diazoalkane and allene addition reaction leading to 3-alkylidene-4,5-dihydro-3//-pyrazoles. ... 

Alcohol adducts of norbornadienepalladium complexes with further allene addition gives nor-tricyclene ligands 38 which have allyl complex side chains. ... 

A study of the influence of silica gel surfaces on the photochemical addition of allene to a series of cyclic enones has been carried out. Using this technique cycloaddition occurs to the more hindered face of the enone. A typical example of allene addition, where addition takes place to the less hindered face, is reported by Piers et al. in the photoaddition to the enone (65) which affords the four isomeric products (66) in ratios of 40 51 6 3. The two major products (66a) and (66b) were used as starting materials for total syntheses of naturally occurring compounds of the stemodane type. ... 

Adding a catalytic amount of an alkyne to the reaction in Equation 1.63 indeed enhanced the yield dramatically. The quantitative yield for the activation step obtained using 3-hexyn-l-ol made this alkyne the one of choice as the activator for the allene addition. Taking advantage of this atom economic synthesis of 1,3-dienes by employing the [4 + 2] cydoaddition then allows complex cyclic entities to be available with high atom economy. 

Three syntheses of this compound have been achieved by the Wiesner group. In two of them an allene addition to a vinylogous amide was a key step while in the third and most direct synthesis a Michael addition to the vinylogous amide system was used in one of the ring-forming reactions. 

The reactions of allenes with nitrones were promoted by the presence of an electron-wdthdrawing group on the allene. Addition took place across the activated double bond <88JOC955>. The alternative mode of addition was achieved by using the allene equivalent (51) (Scheme 12) <89JOC8io>. 

If the alkene is a cumulative diene, that is, allene (1,2-propadiene [CH2=C=CH2]) or a substituted allene, addition can occur once and/or twice (Equation 9.24),... 

A number of allyl-type hydrocarbon units have been bound to the diiron centre. McGlinchey and co-workers have reported the formation of 30, a metal-stabilized disjoint hydrocarbon, from the reaction of tetrabromodurene with iron carbonyls,which is somewhat similar to the coupled product 17 of allene addition to 11 (Scheme 2). Monosubstituted allenes (R=Bu OMe, C02Me, GH2C02Et) have also been shown to react with Fc2(GO)9 to give complexes containing one 31 and two 32 allene moieties. ... 

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