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[2] The addition of the two molecules typically proceeds in a step-wise fashion to the addition product, usually in equilibrium, and with loss of a water molecule (hence the name condensation). [3] The reaction may otherwise involve the functional groups of the molecule, and is a versatile class of reactions that can occur in acidic or basic ...
The reaction is named after James Cooper Duff. [2] The reaction requires strongly electron donating substituents on the aromatic ring such as in a phenol. Formylation occurs ortho to the electron donating substituent preferentially, unless the ortho positions are blocked, in which case the formylation occurs at the para position. [3]
When determining the overall rate law for a reaction, the slowest step is the step that determines the reaction rate. Because the first step (in the above reaction) is the slowest step, it is the rate-determining step. Because it involves the collision of two NO 2 molecules, it is a bimolecular reaction with a rate which obeys the rate law = [()].
The reaction is a three-step process in which the alcohol first undergoes a Mitsunobu reaction with an arenesulfonylhydrazine in the presence of triphenylphosphine and diethyl azodicarboxylate. Unlike hydrazone -synthesis reactions, this reaction occurs on the same nitrogen of the hydrazine that has the arenesulfonyl substituent.
Although, the need for sodium metal limits the functional group tolerance of the reaction, compared to more modern cyclization reactions (e.g. Yamaguchi esterification, ring-closing olefin metathesis), the acyloin condensation continues to be used in the synthesis of complex natural products for the preparation of challenging ring systems. [9]
The reaction of quadricyclane with DEAD is a 2σ + 2σ + 2π cycloaddition that on water takes place within 10 minutes at room temperature with 82% yield. The same reaction in toluene takes 24 hours at 80 °C with 70% yield. An emulsion reaction in fluorinated cyclohexane takes 36 hours and the neat reaction takes even longer (48 hours).
In organic synthesis, the complex diethylaniline·borane (DEANB) is used as a reducing agent. [4] Diethylaniline and dimethylaniline are both used as acid-absorbing bases. The advantage to the diethyl derivative is that [C 6 H 5 NEt 2 H]Cl is non-hygroscopic, in contrast to [C 6 H 5 NMe 2 H]Cl. [5]
The reaction is also stereoselective because the enamine addition occurs with a diastereomeric preference for trans addition without formation of the cis isomer. This is in contrast to traditional Diels–Alder reactions, which are stereospecific based on the alkene geometry. Scheme 2. regio- and diastereoselective Povarov reaction