10596-05-1Relevant articles and documents
A NOVEL ZIRCONIUM-CATALYZED HYDROALUMINATION OF OLEFINS
Negishi, Ei-ichi,Yoshida, Tadao
, p. 1501 - 1504 (1980)
Sterically hindered trialkylalanes, such as triisobutylalane, react with olefins at or below room temperature under the influence of a catalytic amount of Cl2ZrCp2 to effect hydroalumination of the olefins.The reaction can tolerate certain hetero-functional groups, such as OH, SPh and Br, which tend to interfere with previously reported hydroalumination procedures.
An Inexpensive Air-Stable Titanium-Based System for the Conversion of Esters to Primary Alcohols
Reding, Matthew T.,Buchwald, Stephen L.
, p. 7884 - 7890 (2007/10/03)
Polymethylhydroxiloxane, when combined with titanium(IV) isopropoxide, provides a convenient system for the conversion of esters to the corresponding primary alcohols in the presence of a wide range of functional groups.Reactions are carried out as mixtures of the neat reaction components; workup with aqueous alkaline THF affords primary alcohols in good to excellent yields.The system tolerates primary alkyl bromides and iodides, olefins, epoxides, and alkynes.Steric differentiation of methyl and tert-butyl esters is also possible.The results observed in the parent and related reactions argue against pathways involving Lewis-acid catalysis and anionic hydridosilicate-mediated reductions, and instead support a neutral titanium hydride complex or strongly associated titanium/silane complex as the active reducing agent.
Hydroboration. 57. Hydroboration with 9-Borabicyclononane of Alkenes Containing Representative Functional Groups
Brown, Herbert C.,Chen, Jackson C.
, p. 3978 - 3988 (2007/10/02)
The hydroboration of alkenes containing representative functional groups was examined with 9-borabicyclononane (9-BBN) in order to extend the hydroboration reaction for the preparation of functionally substituted organoboranes.Terminal alkenes containing a remote functional group are hydroborated with a remarkable regioselectivity (>=98percent terminal), producing the corresponding stable organoboranes. 9-BBN hydroborates the allylic derivatives so as to place boron essentially on the terminal carbon atom (>=97percent).The directive effect is further enhanced (>=99percent) in the case of β-methylallyl derivatives.The hydroboration of crotyl derivatives attaches boron predominantly at the 2-position, followed by an elimination-rehydroboration sequence.However, crotyl alcohol can be protected against elimination as the tert-butyl or tetrahydropyranyl ethers.The hydroboration-oxidation of ethyl crotonate involves a series of elimination, hydroboration, and condensation processes.In the vinyl, crotyl, and isobutenyl systems, the mesomeric effect of the substituent favors the placement of boron at the β-position, while the inductive effect favors the α-position, with the former effect predominating in most cases.Acyclic β-substituted organoboranes undergo rapid elimination.Nonpolar solvents and lower reaction temperatures decrease the rate of elimination.However, those derived from cyclic vinyl derivatives are relatively stable under neutral conditions, undergoing facile elimination in the presence of a base.
