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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: sharbeldam on June 07, 2019, 01:20:06 PM

Title: Disiamylborane
Post by: sharbeldam on June 07, 2019, 01:20:06 PM

Is it true that Disiamylborane (Sia2BH) only reacts with terminal alkynes to produce aldehydes? it does not react with internal alkynes? and if I need to convert terminal alkynes to aldehydes, must i use the Sia2BH reagent? or would the normal B2H6 (hydroboration) work as well?

Thanks

Title: Re: Disiamylborane
Post by: sjb on June 08, 2019, 02:41:03 AM

Consider sterics and why Sia₂BH might be effective. Compare to borane BH₃

Title: Re: Disiamylborane
Post by: sharbeldam on June 08, 2019, 03:45:14 AM

I tried, I cant tell whats the consequence of that though, I tried to search online but it does not show me the difference in the result

Title: Re: Disiamylborane
Post by: sharbeldam on June 08, 2019, 03:13:20 PM

Because its more steric than borane it should be more selective for the terminal alkene but my question is, would it also react with an internal alkyne? and would a borane (BH3, normal hydroboration) react with a terminal alkene? or do we need the sterically hindered groups (alkyl or sia) attached to Boron for the terminal alkynes?