Functional groups size comparison

In order to explore the generality of this new domino reaction the conversion of various primary amines with 2-341 and the cyclohexane analogue was investigated (Scheme 2.81). For example, the reaction proceeds with high yields when benzyl- or (2-phenylethyl)amine are used (entries 1 and 2). In comparison, sterically more hindered amines such as 2-butylamine produced much lower yield (entry 4) Furthermore, the reaction tolerates other functional groups, such as an unprotected hydroxyl group (entry 5), and variation of the enone ring size is possible (entries 6 and 7). More recent results have revealed that the addition of Sn(OTf)2 or In(OTf)2 makes the transformation more reliable. 

The direct comparison of 1 and 2 in a variety of RCM reactions also indicates a presumably close relationship between these catalysts (Table 1) [6]. Both of them give ready access to cycloalkenes of almost any ring size > 5, including medium sized and macrocyclic products. Only in the case of the 10-membered jasmine ketolactone 16 was the yield obtained with 2a lower than that with lc this result may be due to a somewhat shorter lifetime of the cationic species in solution. However, the examples summarized in Table 1 demonstrate that the allenylidene species 2 exhibit a remarkable compatibility with polar functional groups in the substrates, including ethers, esters, amides, sulfonamides, ketones, acetals, glycosides and even free hydroxyl groups. 

As can be seen in Table 2.17, increasingthe R group size from H to Me to Phe top-tBuPhe (Ia,Ib, Ic, and Id, respectively )led to a steady increase in binding affinity for the 6-opioid receptor from about 6 fjM to about 8 nAf as predicted (242). Most important, the selectivity for the 8-opioid receptor versus the /a-opi-oid receptor also increased very substantially from nonselective to over 2000-fold selective (Table2.17), which actually is somewhat more selective than DPDPE or [(2S,3i )TMT ] DPDPE (see Table 2.16 for comparison). In the functional assays that make use of the classical guinea pig ileum (GPI, for the /i-re-ceptor) and mouse vas deference (MVD, for... 

The distance matrix describes the distances between all atoms (or functional groups) of a molecule. It is the three-dimensional counterpart of the molecular topology. A direct comparison of distance matrices is normally not possible because the size and appearance of the matrix depends on the atom numbering in the molecules. 

The organics were extensive ) characterised, as described in Chapter 4. Differences such as functional group content, size, charge, and hydrophobicity will influence the fouling behaviour if these properties are responsible for flux decline. Figure 7.20 shows a comparison of the different organics filtered through a TFC-S membrane. 

Table I. A Comparison of Size for Some Functional Groups (Data from Reference 1)...

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