Destroyer 2011 OC question 29 help, please

[yueru]

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Can you help me with this question? I was cofused by the last step.
Thanks a lot!!

 

[herkulease]

surprised, a new question. Figured he just shuffle stuff around. anyhow

Last step is a substitution reaction.

TsO- is a good leaving group.

OCH3 is a good nucleophile.

Should be Answer C.

 

[yueru]

Why not E2 for last step: OCH3: strong base and strong nuc
TsO is on 2º C?

surprised, a new question. Figured he just shuffle stuff around. anyhow

Last step is a substitution reaction.

TsO- is a good leaving group.

OCH3 is a good nucleophile.

Should be Answer C.

 

[bharat008]

Why not E2 for last step: OCH3: strong base and strong nuc
TsO is on 2º C?

You are right!! Usually if you have secondary Carbon then most likely you will have E2 product as your major and SN2 as your minor product. But this is one of the exceptions, OTs is a really good leaving group since its resonance stabilized; therefore substitution occurs and NaOCH3 acts as a nucleophile..

 

[yueru]

Thank you!!

You are right!! Usually if you have secondary Carbon then most likely you will have E2 product as your major and SN2 as your minor product. But this is one of the exceptions, OTs is a really good leaving group since its resonance stabilized; therefore substitution occurs and NaOCH3 acts as a nucleophile..