Group postulates

A set of operators A, B,... in a vector space L forms a group if the operators satisfy the group postulates. Hence the product of the operators A and D means the single operator C such that... 

With regard to the mechanism of this new type of reaction, the Jorgensen group postulated enamine formation, by addition of the catalyst to the nitrone, followed by hydroxylamine elimination [132], Subsequent aldol-type reaction of this enamine with the carbonyl component and release of the proline catalyst by exchange... 

In the following years, several groups postulated the involvement of triplexes in various photochemical electron transfer reactions [104]. 

Symmetry properties of a molecule (molecular ion) are described by its symmetry point group. This group is a collection of its symmetry operations R (group elements) which must satisfy group postulates. There are several types of the symmetry... 

The question of the thermodynamic stability of carbon onions has been subject to controversial discussion ever since their discovery. Some groups postulate them to be the thermodynamically most stable phase for this size of particles, while... 

In addition, the same group postulated the formation of the mixture of bases in acid to involve transannular nucleophilic attack of N-4 on the protonated amide with subsequent dehydration and cleavage of the C-20-C-21 bond. The resulting cation 174 has several possible fates, depending on four alternative proton losses and stabilization of the carbonium ion by addition of water (see Scheme 4). The structure of rhazinilam was also confirmed by total synthesis, and this will be described in Section IV, A,27 of this chapter. 

The eight sym-ops of D2/1 are said to constitute a group because they comply with several group postulates [9, 10] ... 

In addition to conforming to the group postulates, as all groups must, D2A obeys the commutative rule, according to which the result of performing any... 

All efforts were therefore concentrated on examining the potential of a-phenylglycidate as an afiinity label. Structurally it is very similar to mandelate. Moreover, the-CHz-group of the epoxide ring seemed strategically placed to intercept the key basic group postulated to be involved in the a-proton extraction process associated with enzymic catalysis ... 

Given the similarity in structural components between the flinderoles and the borreverines, multiple research groups postulated related biosyntheses for the two structural classes. Our initial impression was that they would be formed by the dimerization of two isoprenylated methyltryptamines in the presence of acid. A search in the chemical literature quickly turned up a study that postulated and validated that veiy idea for the borreverines. 

Figure 5.3. Sweet tasting molecules showing the AH-B-X groups postulated by Shallen-berger-Kier hypothesis. The numbers in parenthesis are the degrees of sweetness relative to sucrose.

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