Organic chemists, interests

This model was not cast in the terms usually used by organic chemists, and thus its adoption required considerable time. However, it led in an obvious way to the 4n+2 rule for aromaticity which has been a mainstay of organic chemists interested in the subject. It led to the prediction that the following ions would be stabilized in a fashion similar to that for benzene. 

To overcome this problem, Whitesell and Felman [19] introduced the use of a C2-symmet-ric chiral auxiliary, (S,S)-trans 2,5-dimethylpyrrolidine, to generate the enamine (reaction E). Rotation around the N-C bond simply results in a topomerization [5] and, therefore, in the reduction of the number of the non-stereocontrolled attacks by the electrophile. Since the appearance of this seminal paper, C2-symmetric reagents have become a standard tool in the hands of the organic chemists interested in stereoselective synthesis [20]. 

The photochemistry of carbonyl compounds has been extensively studied both in solution and in the gas phase. It is not surprising that there are major differences between the two phases. In the gas phase, the energy transferred by excitation cannot be lost rapidly by collisions, whereas in the liquid phase, the energy is rapidly transferred to the solvent or to other components of the solutions. Solution photochemistry will be emphasized here, since most organic chemists interested in either mechanistic studies or preparative photochemistry have studied this aspect of the problem. 

In 2(K)3, Rawal reported the use of TADDOLs (tetraaryl-1,3-dioxolan-4,5-dimethanol) as chiral H-bonding catalysts to facilitate highly enantioselective hetero-Diels-Alder reactions (393). Not surprisingly, this impressive protocol has soon found its way into the repertoire of organic chemists interested in natural product synthesis (394, 395). 

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