[davidaff]

Hi guys,

I'm having trouble with a question...

So far I have the following reagents/conditions but I'm not so sure on them..

1. KH/CH3-I
2. Protecting group (Acetal)
3. ??
4. PPh3=CHCOOEt
5. Deprotecting group (H3O+)

I'm having most trouble adding the ethyl group right in the centre which I think may be step three...

Also If I add the H3O+ after the Wittig reaction will it favour the acetal group or the ester?

Appreciate any help I can get..thanks!

[sjb]

Hi guys,

I'm having trouble with a question...

So far I have the following reagents/conditions but I'm not so sure on them..

1. KH/CH3-I
2. Protecting group (Acetal)
3. ??
4. PPh3=CHCOOEt
5. Deprotecting group (H3O+)

I'm having most trouble adding the ethyl group right in the centre which I think may be step three...

Also If I add the H3O+ after the Wittig reaction will it favour the acetal group or the ester?

Appreciate any help I can get..thanks!

I think you may have some chemoselectivity issues in step 1. Maybe leave the methylation until later and protect the aldehyde first?

How can you add 1,4 to a carbonyl?