Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Organotin hydrides reactivity

Unsymmetrical functional tetraorganotins are generally prepared by tin hydride addition (hydrostaimation) to functional unsaturated organic compounds (88) (see Hydroboration). The realization that organotin hydrides readily add to atiphatic carbon—carbon double and triple bonds forming tin—carbon bonds led to a synthetic method which does not rely on reactive organometatiic reagents for tin—carbon bond formation and, thus, allows the synthesis of... [Pg.68]

Finally, some important functional groups, notably the keto group and the carboxylic acid group, cannot be reduced with organotin hydrides. However, these groups can be reduced provided they are converted into a more reactive group. [Pg.796]

Organotin hydrides are advantageous as reductants in terms of their facile availability, stability, and reactivity. - Almost all tin hydrides are liquids, and stoichiometric tin-hydrogen bonds can be used. In general, the tin hydride reductions have been performed under radical conditions using initiators such as azobisisobutyroni-trile (AIBN), triethylborane, and UV irradiation. The reduction of organic halides and pseudohalides by tri- -... [Pg.342]

Reductive dehalogeuation of alkyl halides. Lithium aluminum hydride has commonly been used only for reductive dchalogenation of reactive substrates organotin hydrides, for example tri- -btityltin hydride (I. 1192-1193 2, 424 3, 294), have been used for reduction of inert halides. Recently JeflToid ei al. have reported that supposedly inert halides are reducible by lithium aluminum hydride. Thus the vinyl halide (I) is reduced to (2, endb-2-phenylbicyclo[3.2. l]octene-3) by lithium aluminum hydride in refluxing ether (24 hr.). 3-Bromobicyclo[3.2.l]octene-2 is reduced to the parent... [Pg.292]

The reduction of chlorodeoxy sugars has been achieved [31,32] in high yield by means of tributyltin hydride in the presence of 2,2 -azobis(2-methylpropionitrile). The reaction with methyl 2,3-di-0-acetyl-4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside at 60°C gave [31] methyl 2,3-di-0-acetyl-6-chloro-4,6-dideoxy-ot-D-xylo-hexopyranoside as the main product. A free-radical mechanism has been proposed [33] for the reduction of alkyl halides by organotin hydrides. In accordance with this proposal, the presence of the radical initiator 2,2 -azobis(2-methylpropionitrile) was essential for the reduction of chlorodeoxy sugars moreover, the relative reactivities of the two chlorine atoms in methyl 2,3-di-0-acetyl-4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside follow a free-radical order. [Pg.62]

Many reactions have been carried out with the help of organic hydrides of the elements of the main group IV (except lead) which have resulted in the synthesis of new groups of compounds. Organotin hydrides were found to be especially versatile 189). The reactivity of organolead hydrides has presented a challenging problem that has only been recently solved. Some... [Pg.266]

Organolead hydrides are more reactive towards C=C and C=C bonds than are the corresponding tin hydrides. Therefore, it is very easy to add lead hydrides completely to unsaturated compounds by placing the latter into the mixture of RsPbX and organotin hydrides. Compare Section III, D,2. An analogous exchange of vinyl and hydrogen... [Pg.271]

As is true for hydrostannation, acetylenes are also more reactive than the olefins toward hydroplumbation. Acetylenedicarboxylic acid dimethyl ester and ethyl propiolate 152) add Bu3PbH at — 50° C (used as a pure substance, or made in situ from organotin hydrides) spontaneously and without side reactions. Me3PbH adds in the same smooth manner to cyanoacetylene and methyl propiolate 165). Phenylacetylene reacts under the same conditions but in a side reaction Pb is precipitated and H2 evolves. After a short while starting materials disappear if excess of lead hydride is used. The IR spectrum shows absorption at 990 cm , which is in accordance with a trans adduct 152,194). [Pg.281]

The reactivities of organotin hydrides [24] and chromium (II) complex [25] toward alkyl halides are also in the order of tertiary > secondary > primary alkylhalides. However, this trend is much stronger with the ate complex of 9-BBN than that with these reagents. Consequently, the high selectivity, gentleness, and convenience exhibited by the reagent has the practical synthetic application (Eq. 25.20) Benzylic halides are also reduced easily (entries 11-13, Table 25.10), whereas aryl and vinylhalides are inert (entries 19,20). Benzylic geminal dihalides are reduced stepwise (entries 16, 17). The reaction of 1-phenylallyl-chloride [26] which also contains 33% of cinnamyl chloride with an equiv of ate complex of 9-BBN affords mixture of allylbenzene (36%) and 3-metliylstyrene (66%). [Pg.416]

Baba and coworkers reported the unusual reactivity of highly coordinated tin compounds such as organotin(IV) enolates or organotin(IV) hydrides. NMR studies disclose the existence of five-coordinated tin enolate arising from the addition of certain ligands . In particular, the coordination to tin enolates by a bromide anion (from Bu4NBr) shows novel types of selective reactions. ... [Pg.59]

Many organotin compounds, and in particular those that contain special substituents and are in some cases difficult to obtain in other ways, can be prepared by addition of organic tin hydrides to compounds containing double or triple carbon-carbon bonds. Tin hydrides containing three organic groups add to reactive double bonds and to acetylenes even on mere heating at 80 to 100° 437 e.g. ... [Pg.800]


See other pages where Organotin hydrides reactivity is mentioned: [Pg.67]    [Pg.795]    [Pg.797]    [Pg.661]    [Pg.110]    [Pg.41]    [Pg.41]    [Pg.661]    [Pg.257]    [Pg.671]    [Pg.70]    [Pg.306]    [Pg.423]    [Pg.53]    [Pg.71]    [Pg.853]    [Pg.1335]    [Pg.1582]    [Pg.67]    [Pg.342]    [Pg.1335]    [Pg.1582]    [Pg.245]    [Pg.85]    [Pg.448]    [Pg.448]    [Pg.258]    [Pg.664]    [Pg.672]    [Pg.598]    [Pg.448]    [Pg.39]    [Pg.882]    [Pg.428]   
See also in sourсe #XX -- [ Pg.549 , Pg.550 , Pg.551 ]

See also in sourсe #XX -- [ Pg.416 ]




SEARCH



Organotin hydrides

© 2024 chempedia.info