Biichi rearrangement

Allylic alcohols with a trans double bond give product mixtures in the Still-Wittig rearrangement cf. equation 7 ). Advantageously, such substrates e.g. 98) can be converted to homoallylic alcohols with 100% chirality transfer by the Biichi rearrangement (equation 25). ... 

Another example, which takes place in weakly basic conditions, is provided by the key step of the synthesis of aromadendrene (111 accomplished by Biichi and coworkers [4], in which a cw-decalin system (9) rearranges to a hydroazulene system (10) through a process induced by activated AI2O3 (Scheme 7.3). 

This [3,3] sigmatropic rearrangement process, which represents a variant of the well-known Biichi reaction, does proceed through a transition state geometry which is boatlike in character. The rearrangement reaction has been applied to other lactones as well. One rather interesting example is provided by the rearrangement of the cls-fused lactone (646) to the bicyclic carboxylic acid (647 Scheme 148). 

Later examples of the oiefination of carbonyl compounds, which are extremely sensitive towards add or base catalyzed rearrangements, have been given by G. Biichi and by R.B. Woodward. 

The Still-Wittig rearrangement of stannylated cis-ethers (11) gives trans homoallylic alcohols (12) selectively (equation 5). If the underlying alcohols (R = Me) are rearranged under Biichi s conditions (DMF acetal, xylene, reflux), trans selectivity is achieved, too, but yields are lower (41-49%). ... 

The oxidative rearrangement route (chapter 5) has been used in many syntheses of cyclo-pentenones. Biichi s route39 to cis jasmone 1 simply involves treating the cyclopentenone 136 with MeLi and oxidatively rearranging the product 137 directly to cis jasmone 1. 

Paal-Knorr Pyrrole Synthesis Parham Cyclization Passerini Reaction Patemo-Biichi Reaction Pauson-Khand Reaction Payne Rearrangement Pechmann Condensation Pechmann Pyrazole Synthesis Pellizzari Reaction Pelouze Synthesis Periodic Acid Oxidation Perkin Alicyclic Synthesis Perkin Reaction Perkin Rearrangement Perkow Reaction Peterson Reaction... 

Biichi et al. reported the total synthesis of atrovenetin via a base-promoted site-selective Claisen rearrangement followed by the formation of a benzofuran framework 111 [83]. 

A reaction which transforms allylic alcohols to homologous 0,7-unsaturated amides by means of a 2,3-sigmatropic process was first described by Biichi. When an allyl alcohol is heated with IV -di-methylformamide acetal, a rearrangement occurs apparently involving a nucleophilic carbene as an intermediate, leading to a product with 95-100% ( )-geometry of the double bond (Scheme 47). 

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