Miscellaneous Reactions of Synthetic Importance

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Presentation transcript:

Miscellaneous Reactions of Synthetic Importance

Mitsunobu Reaction The Mitsunobu Reaction constitutes a reliable way to activate an alcohol as a leaving group, thus allowing an Sn2 substitution by selected nucleophiles. The nucleophile is introduced as its conjugate acid, with the conjugate acids of the best nucleophiles having pKa < 7.

The Wittig Reaction

Mechanism As a rule of thumb, ‘stabilized’ ylides (those having additional carbanion-stabilizing groups) produce alkenes of E geometry, while ‘unstabilized’ ylides produce alkenes of Z geometry.

Horner-Wadsworth-Emmons Reaction

Mechanism Under the usual conditions, the HWE reaction tends to prefer formation of the alkene with the E geometry.

However, under specialized conditions, shown below, the alkene of the Z geometry can be produced.