Why is there no rearrangement DESTROYER 2016

[fan2342]

Why doesn't this do ring expansion?

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[fan2342]

Also, how is 206 not e?

 

[deleted816661]

Also, how is 206 not e?

A palindrome in genetics is not like English might be like (word forward=word backwards). Here, it means that the 5' and 3' ends of a nucleotide, usually a restriction enzyme site, are complementary. So, it is 5' CCTAGG 3'. 5' CCT is complementary to the 3' GGA.

Why doesn't this do ring expansion?

This is a hydroboration oxidation reaction of an alkene. Therefore, you add anti markovnikov.

 

[fan2342]

A palindrome in genetics is not like English might be like (word forward=word backwards). Here, it means that the 5' and 3' ends of a nucleotide, usually a restriction enzyme site, are complementary. So, it is 5' CCTAGG 3'. 5' CCT is complementary to the 3' GGA.


This is a hydroboration oxidation reaction of an alkene. Therefore, you add anti markovnikov.

There's no carbocation in hydroboration correct? And wow I don't know what I was thinking. Thanks

 

[kimball]

Nope

 

[DAT Destroyer]

Why doesn't this do ring expansion?

You are indeed the perspicacious student ! An exocyclic double bond on a 3 or 4 membered ring does indeed indicate a rearrangement of some sort. HOWEVER, not here. The hydroboration reaction was developed by my dear friend Dr. Herbert C. Brown. I have met him a few times, and he was the kindest man I ever known. This reaction earned Dr. Brown the 1979 Nobel Prize in Chemistry ! No rearrangements occur with this reaction since no carbocation or even carbanion is involved. You need not bother yourself with the mechanistical details. You simply must remember to do an Anti-Matkovnikov addition, with syn stereochemistry. This reaction is usually employed to give alcohols.

Hope this helps.

Dr. Romano