Alkenyl derivatives

The structure of CpZnMe (24) has been determined in both the gas phase (by electron diffraction) and in the crystal. The gas phase structure (Csu) is iso-structural with that of CpBeMe. The Cp-M interaction in (24) is weaker due to 

The thermal stability of bis-allylzinc is in the sequence (CH2=CHCH2)2Zn (25) (CHa=CMeCHa)2Zn (MeCH=CHCH2)2Zn (Me2C=CHCHa)2Zn. Below -125 C, (25) exists as a static a-allylic species but at room temperature all are rapidly equilibrating mixtures of (T-allylic forms. Above 100 °C, decomposition leads to bisallyl products.  

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The prototype of a pure ethylenediamine is tripeleimamine antazoline [91-75-8] C27H22N2, belongs to the same family of compounds. Several well-known alkylamines in addition to chlorpheniramine are known. Hexchlorpheniramine maleate [2438-32-6] and triprohdine monohydrochloride monohydrate [6138-79-0] an alkenyl derivative, are two examples. 

Organoboranes can also be used to construct carbon-carbon bonds by several other types of reactions that involve migration of a boron substituent to carbon. One such reaction involves a-halo carbonyl compounds.20 For example, ethyl bromoac-etate reacts with trialkylboranes in the presence of base to give alkylated acetic acid derivatives in excellent yield. The reaction is most efficiently carried out with a 9-BBN derivative. These reactions can also be effected with (3-alkenyl derivatives of 9-BBN to give (3,y-unsaturated esters.21... 

A second group of aromatic substitution reactions involves aryl diazonium ions. As for electrophilic aromatic substitution, many of the reactions of aromatic diazonium ions date to the nineteenth century. There have continued to be methodological developments for substitution reactions of diazonium intermediates. These reactions provide routes to aryl halides, cyanides, and azides, phenols, and in some cases to alkenyl derivatives. 

ADDITION OF THE Os—H BOND OF OsHCI(CO)(P Pr3)2 TO CARBON-CARBON TRIPLE BONDS FORMATION OF ALKENYL DERIVATIVES... 

The reactivity of OsHCl(CO)(P Pr3)2 toward alkynes depends on the type of alkyne used. Whereas phenylacetylene, propyne, and acetylene react by insertion to give the five-coordinate alkenyl derivatives Os ( >CI I=CHR Cl(CO)(PIPr3)2 (R = Ph, Me, H),31,33 the reaction with methylpropiolate affords a mixture of Os C(=CH2)C(OMe)0 Cl(CO)(P,Pr3)2 and 0s ( )-CH=CHC02Me Cl(C0) (P Pr3)234 (Scheme 3), and tert-butyl acetylene and diphenylacetylene are inert. 

The complex OsHCl(CO)(P Pr3)2 also reacts with diynes.35 Thus, it has been reported that the treatment of this compound with 0.5 equiv. of 1,7-octadiyne affords, after 6 h at 333 K, the binuclear p,-bis-alkenyl derivative (P Pr3)2(C0)C10s CH=CH(CH2)4CH=CH OsCl(CO)(P,Pr3)2 in 83% yield (Eq. 3). 

In toluene at room temperature, the complex OsHCl(C=CHCy)(CO)(P,Pr3)2 evolves after 3 days into the alkenyl derivative Os ( )-CH=CHCy Cl(CO)... 

In agreement with the nucleophilic character shown by the Cp atom of the alkenyl derivative OsHCl ( ,)-CH=CHCy (CO)(PiPr3)2, the hctcrodinuclear-p-bisalkenyl complex (P Pr3)2(CO)ClRu ( )-CII=CII(CII2)4CII=CH-( ) OsCl (CO)(P Pr3)2 reacts with HC1. However, interestingly, only the Cp atom of the Os-alkenyl unit is attacked. Thus, the treatment of the p-bisalkenyl complex with the stoichiometric amount of a toluene HC1 solution selectively affords (P,Pr3)2(CO)ClRu ( )-CH=CH(CH2)5CH OsCl2(CO)(P,Pr3)2 (Scheme 10). This observation proves that under the same conditions, the Cp atom of the alkenyl... 

Russell and coworkers have made an extensive study of the photolytically initiated substitution reactions of a variety of reagents with 1-alkenyl derivatives of SnBu333,34, the general reaction being as shown in reaction 26. The process is thought to involve addition-elimination in a free radical chain mechanism, illustrated in Scheme 3. 

A similar reaction of pyrroles 20 with acrylates provides the C-2 substituted a-alkenyl derivatives 21 in 24-91% yield [29]. The 2,6-dichlorobenzoyl protecting group is noteworthy as it prevents cyclization of the phenyl group onto the pyrrole ring (vide infra). 

A one pot route to nido-1,6-diiodo-tctracarba-nuio-hcxaborane derivatives is depicted in Scheme 3.2-32. After iodoboration of the alkynes with BI3 the dehaloge-nation of the alkenyl derivatives presumably leads to dimerization and rearrangement to give structurally characterized 1,6-diiodo-nido-carboranes 56d [81]. 

Kinetics of the acid hydrolysis of A-alkenyl derivatives of phenoxazine, phenoth-iazine, and carbazole in aqueous dioxane suggest an ASe2 mechanism, based on the activation parameters and isotope effects. ... 

Retention of the confignration is observed in all the reactions involving the cyclohexyl and alkenyl derivatives. 

Similar 1,2,3-diheterocyclizations have been performed by addition of other Af, N- or Al,5-dinucleophiles, such as pyridine-2-thiol, 2-aminopyridine, 2-aminothia-zole, thioisonicotinamide, and l//-benzotriazole, to complexes 6 and 46 giving rise to the formation of the five- and six-membered cyclic alkenyl derivatives 96-100 (Fig. 19) [289, 291,292],... 

Unfortunately, the vinyl anion undergoes protonation under these reaction conditions and leads to the simple aUcene 92 as the major product. It has been suggested that the proton source is actually the tosylhydrazone monoanion 88 , and that the basicity of 91 is strong enough to abstract an a proton from the unreacted tosylhydrazone monoanion 88 or even from 89 by ortijo-metalation of the tosyl ring. Thus, in order to avoid this protonation in the reaction, an excess of base (>3 equivalents) was required to obtain good conversion into alkenyl derivatives. 

Alkenyl derivatives of benzyl alcohol and related naphthalene substrates undergo a rapid Pd-catalysed cyclisation to U/-2-benzopyrans and the bettzologues (Scheme 14) <99TL4871>. 

A variety of fluorinated alkenyl zinc reagents such as CF2=CFZnCl, CF2=CHZnCl, E and Z-RCF = CFZnCl have been prepared by the first method (Scheme 54). In the presence of palladium catalyst, these fluorinated alkenyl zinc reagents undergo cross-coupling reactions with aryl iodides, vinyl iodides, acid chlorides and 1-iodo-l-alkynes to give the corresponding fluorinated alkenyl derivatives [127, 146-153], which have been utilized in the synthesis of fluorinated codlemones [154]. Typical examples are outlined below (Scheme 55). 

The cyclization of A-alkenyl derivatives of resin-bound peptides by ruthenium-catalyzed ring-closing metathesis has been investigated [426-428]. These reactions do not proceed well on insoluble supports, and cyclizations in solution are generally more successful. 

Even antimony pentafluoride is able to add across the C=C bond. As shown [124], reaction with CH2=CF2 results in the formation of an additional product -tris(/ , p, /)-trifluoro-ethyl)antimony difluoride. Formation of the alkenyl derivatives of antimony in reaction with CF2=CC1-CF=CF2 (Eq. 75) is another example ... 

Certain oi-alkenyl derivatives are obtained from reaction of a silicon-silicon containing Grignard reagent with allyl bromide, as exemplified by the equation... 

A rhenium complex, [ReBr(CO)3(thf)]2, has been found able to catalyse the inter-molecular reactions of 1,3-dicarbonyl compounds with terminal alkynes to give the corresponding alkenyl derivatives in excellent yields (Scheme 6).35 These reactions could apply to an intramolecular version and gave the corresponding cyclic compounds quantitatively. Tributylphosphine has been found to be a superior catalyst for the a-C-addition of 1,3-dicarbonyl compounds to electron-deficient alkynes.36... 

The supporting electrolyte is anodically oxidized to radicals, which abstract ohydrogen from the ether to form alkoxymethyl radicals that are subsequently oxidized to cations. An analogous route leads to alkenyl derivatives. 

Organotin 1,2-dithiolate complexes were featured in many studies the ligands used include aliphatic derivatives, e.g. ethane-1,2-dithiolate -SCH2CH2S-(EDT), -SCH2CHMeS-, alkenyl derivatives, e.g. -SCH=CHS-, maleonitriledithiolate (MNT), aryl derivatives, 1,2--SC6H4S (BDT) and toluene-3,4-dithiolate (TDT), as well as heterocyclic derivatives, l,3-dithiane-2-one-4,5-dithiolate (DMIO) and l,3-dithiane-2-thione-4,5-dithiolate (DMIT)191. 

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