[astolcers]

I am having a very difficult time finding Box 4 as well as the epoxide that is formed. Does anyone have any ideas? An image of the problem is attached, this is the smiles string for box 2:

[H][C@]12[C@@H](O)C(=O)\C=C\C=C/C3=CSC(=N3)[C@@H](C)NC(=O)C[C@]3(CC[C@]1(C)[S+]23)[C@@](C)(O)C([O-])=O

[billnotgatez]

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[astolcers]

I apologize for not reading rules prior to posting

This is my original though on the epoxide, as it is the only logical place where a hydrogen can be kicked off and an SN2 reaction take place however, I was told this is incorrect.
Smiles String: C[C@H]1NC(=O)C[C@]2(CC[C@]3(C)[S+]2[C@]32O[C@H]2C(=O)\C=C\C=C/C2=CSC1=N2)[C@@](C)(O)C([O-])=O

In part two i know looking for the site of greatest electrophilicity would be how you find where the SN2 takes place, however I have no idea where this would be, the positively charged sulfur? If so that seems like it would cause an additional bond to break and offers no insight on why the hydrogen would leave.

Thanks in advance and again i apologize for not reading the rules.

[Babcock_Hall]

I don't claim to know the answer with certainty, but let me ask you a question.  If attack occurs adjacent to a positively charged sulfur, is a good leaving group created?  Can you think of a common biochemical example of such an attack?

[astolcers]

I would think that having an S+ would be a good leaving group as it will easily accept the C-S bond electrons. The only problem I see with this is that the adjacent carbons are very poor electrophiles as they share a partial negative charge.

[Babcock_Hall]

S-adenosylmethionine was the compounds I was thinking of.  Because the leaving group is a very weak base, it is also a good leaving group.  I am not sure what you mean by the carbon atoms' having a partial negative charge