There are many different ways to synthesise alkenes in organic synthesis. The problem in many cases, especially those in macrocycles or non-cyclic systems is getting good E/Z selectivity. Several methods are possible however, one of the simplest is the peterson olefination. The reaction allows control of E/Z selectivity by the conditions used to remove the silane.
Reaction overview
The Peterson olefination utilises silicon to allow condition
dependent cis/trans selective olefination of aldehydes and ketones.
Basic elimination
The basic elimination conditions favours the syn-product via a proposed penta-substituted Si
intermediate.
Acid Elimination
The acid elimination conditions favours the anti-elimination
to give the trans product.
Summary
The Peterson olefination allows E/Z synthesis without using an expensive chiral catalyist and can provide differing stereoselectivity on the same substrate.
No comments:
Post a Comment