Can any one do organic(288)

15 Answers

39
Pritish Chakraborty ·

I think ans is A)....alkenes don't react with phosphorus ylides, not any reaction I've heard of. The first step is a Wittig reaction, and it gives a =CH2 in place of =O.

1
Manmay kumar Mohanty ·

bro it's B)

39
Pritish Chakraborty ·

But that would be the case if the second reagent were a carbene...Wittig's reagents are not considered carbenes.

1
Manmay kumar Mohanty ·

yaar mujhe bhi kuch samjha mein nahin aa raha hai.

1
Manmay kumar Mohanty ·

Can no one do this? please help yaaro.

1
Manmay kumar Mohanty ·

Can no one do this? please help yaaro.

1
Manmay kumar Mohanty ·

Pleaseee is ko solve kardo I konw it is wittig reaction but can't help myself here.

24
eureka123 ·

i agree with pritish...ans should be a

1
Unicorn--- Extinct!! ·

It is surely a)

19
Debotosh.. ·

yes, the answer looks to be (b)
thats becasue in WITTIG , the decomposition of betaine is the rds ! after the first wittig, then the carbanion opens on the side of benzylic carbon of double bond ! after that there is a "hera-pheri" of bonds and we get the cyclopropane ring !

1
Manmay kumar Mohanty ·

bolne se thodehi ho jayega.Please mechanism karke samjhao Debotosh.

1
Manmay kumar Mohanty ·

hey iska mechanism mujhe nahin aata hai.pleasssse koi to batao.

1
Manmay kumar Mohanty ·

YAR KOI NAHIN BATAYEGA KYA?

1
abhishek sahoo ·

39
Pritish Chakraborty ·

Reopening the debate here :
I did a little research on this and found that the alkene acts as a Michael acceptor here(refer Michael additions).

The group on the top left with the EWG can be taken as the phosphorus ylide. Note the difference though; X is either S, P, or N. There is no EWG present(H can't really be an EWG) but phosphorus ylides are stable, so absence of EWG doesn't matter.

Now here's the catch; notice how bad the leaving ability of phosphorus is. If phosphorus doesn't leave, cyclopropanation nahi ho sakta...
This is what makes up for the catch - the three benzene brothers. Triphenyl phosphine is formed as side product, as -P(Ph)3 leaves and cyclopropanation does take place.
Will come up with a mechanism-diagram for this later.
And if you were wondering how this can happen without C=O, in Manmay's question there are two benzenes side by side which facilitate electron movement by resonance(like in C=O). This is the "opening on the benzylic side of the double bond" debotosh was talking about.

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