Hydroboration. VII. Directive Effects in the Hydroboration of Olefins

Brown, Herbert C.; Zweifel, George

doi:10.1021/ja01502a063

Cited by 126 publications

(104 citation statements)

References 1 publication

Supporting

Mentioning

101

Contrasting

Order By: Relevance

“…The hydroboration of cyclopentene with (9-BBN)2 in CC14 at 25°C exhibits first-order kinetics, first order in (9-BBN)2 only [7]. [7] A typical data set is summarized in Table 1. It is clear that the first-order rate constants remain virtually unchanged throughout the reaction.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Hydroboration kinetics: Unusual kinetics for the reaction of 9-borabicyclo[3.3.1]nonane with representative alkenes

Brown

Wang

Scouten

1980

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

The kinetics of hydroboration of alkenes with 9-borabicyclo[3.3.lnonane dimer, (9-BBN)2, exhibit interesting characteristics. With more reactive alkenes, such as 1-hexene, 2-methyl-1-pentene, 3,3-dimethyl-1-butene, and cyclopentene, the reaction exhibits first-order kinetics, first order in (9-BBN)2 and zero order in alkene. On the other hand, with less reactive alkenes, such as cyclohexene, 1-methylcyclohexene, and 2,3-dimethyl-2-butene, the reaction exhibits three-halves-order kinetics, first order in alkene and one-half order in (9-BBN)2. These kinetics can be accounted for in terms of the following mechanism:(9-BBN)2 -2 9-BBN 9-BBN + alkene --B-alkyl-9-BBN In the case of the more reactive alkenes, the rate-determining step is the dissociation of the dimer. With less reactive alkenes, the reaction of the alkene with the monomer becomes the rate-determining step. For certain alkenes, such as 2-methyl-2-butene and cis-3-hexene, neither of the two steps is a decisive rate-determining step. Therefore, the reaction exhibits kinetic behavior between that of first-and three-halves-order kinetics.The hydroboration reaction is one of the cleanest, most versatile reactions known in organic chemistry (2-5). It makes organoboranes readily available for synthetic purposes [1].

show abstract

Section: Resultsmentioning

confidence: 99%

“…The reaction has been proposed to proceed through a facile 2+2 cycloaddition (7). I O IPC2B-CHCH3 [2] optical purity 98.4%…”

Section: -Bbn + Alkene --B-alkyl-9-bbnmentioning

confidence: 99%

Hydroboration kinetics: Unusual kinetics for the reaction of 9-borabicyclo[3.3.1]nonane with representative alkenes

Brown

Wang

Scouten

1980

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Knochel and co-workers have utilized borane-mediated hydrozincation to form alkylzinc compounds from excess DEZ and B(alkyl)Et 2 [13]. Alkylboranes are readily prepared via anti-Markovnikov hydroboration of olefins [14]. Zinc and boron alkyls undergo facile, reversible exchange of alkyl groups [15].…”

Section: Resultsmentioning

confidence: 99%

Synthesis of bis(7-octenyl)zinc via heterogeneous Ni catalysts

et al. 2014

View full text Add to dashboard Cite

“…It is carried out preferentially along the least congested carbon (anti-Markownikov addition). This regioselectivity can be changed against steric effects (Brown & Zweifel, 1960;Brown & Sharp, 1968;Brown et al, 1974). The existence of two active sites in methyl esters of fatty acids, FAME: the carbon-carbon unsaturation and the ester, make their hydroboration reactions more difficult to achieve.…”

Section: Introductionmentioning

confidence: 99%

Hydroboration of Methyl Esters of Fatty Acids

Mcheik

Hijazi

Diab

et al. 2017

ESJ

View full text Add to dashboard Cite

Hydroboration addition reactions of a boron atom, and hydrogen over unsaturated, have been widely studied. They have excellent access routes to organoborans which have proven to be a very useful synthetic intermediate Matteson, 1987;Smith, 1994). The bill might be on one or other of the two carbons of the unsaturation. It is carried out preferentially along the least congested carbon (anti-Markownikov addition). This regioselectivity can be changed against steric effects (Brown & Zweifel, 1960;Brown & Sharp, 1968;Brown et al., 1974). The existence of two active sites in methyl esters of fatty acids, FAME: the carbon-carbon unsaturation and the ester, make their hydroboration reactions more difficult to achieve. However, it has been demonstrated that reducing the ester groups is much slower than that of olefins (Brown & Keblys, 1964). By using suitable operating conditions, it is possible to limit this secondary reaction and to obtain a selective reaction of carboncarbon double bond (Fore & Bickford, 1959). Others have protecting ester function by a silyl group in order to have a single reactive site (Kabalka & Bierer, 1989).

show abstract

Hydroboration. VII. Directive Effects in the Hydroboration of Olefins

Cited by 126 publications

References 1 publication

Hydroboration kinetics: Unusual kinetics for the reaction of 9-borabicyclo[3.3.1]nonane with representative alkenes

Hydroboration kinetics: Unusual kinetics for the reaction of 9-borabicyclo[3.3.1]nonane with representative alkenes

Synthesis of bis(7-octenyl)zinc via heterogeneous Ni catalysts

Hydroboration of Methyl Esters of Fatty Acids

Contact Info

Product

Resources

About