[glycogrl07]

I am trying to figure out the mechanism for breaking the cyclic ester bond with HCl and CH3OH to form C7H13O2Cl from 3-ethyl-2-oxacyclopentanone.  I thought at first the Cl would act as a Nu on the system, but I don't know then how the extra methyl group is added also. 

Thank you

[azmanam]

first, cyclic esters are named 'lactones.'

second, if those are your only two reagents, then you've got me stumped.  I've got C₇H₁₄O₃ as my product.  Are you sure there isn't a second step with PCl₃ or PPh₃/CCl₄ or something?

[glycogrl07]

sorry...breaking lactone bond

As for the reagents, that is what is given in the question... I actually want to do halogenation, but the alcohol does something in the reaction also, and the bond between the alpha and beta carbons is broken.   I found the reference for the reaction, but I am trying to understand it now.

[azmanam]

Wow.  Those are some pretty harsh conditions.

The first step is just an acid catalyzed transesterification.  Second step is probably chloride mediated S_N2 hydronium ion displacement of the protonated alcohol from the first step.

Bond b/t alpha/beta carbons is not broken.

[glycogrl07]

Thank you for your help.  I think I was getting confused before. But you broke it down and now I wonder what I missed.  It's so simple, now.

Thanks again