12-ring pockets

Figure 405. Partially assembled modern roller press for coal briquetting with two pocketed rings per shaft. (Courtesy of Koppern, Hattingen, FRG)...

Fig. 14. Types of grinders (a) three-pocket, (b) magazine, (c) chain, and (d) ring (22).

Zhn and coworkers have developed SwAr-based macrocyclizadon via biaryl ether formation. The first example of SivAr-based macrocyclizadon for synthesis of model carboxylate-binding pocket C-O-D rings of vancomycin was reported in 1994 fScheme 9.3. ... 

Step 3 of Figure 27.14 Third Cyclization The third cationic cyclization is somewhat unusual because it occurs with non-Markovnikov regiochemistry and gives a secondary cation at C13 rather than the alternative tertiary cation at C14. There is growing evidence, however, that the tertiary carbocation may in fact be formed initially and that the secondary cation arises by subsequent rearrangement. The secondary cation is probably stabilized in the enzyme pocket by the proximity of an electron-rich aromatic ring. 

A tetracyclic triquat system has been applied (ref. 6) in the synthesis of ZSM-18, the first known zeolite to contain rings of three (Si, Al)-0 species (3-rings). The structure of ZSM-18 consists of parallel 12-ring channels equipped with side pockets. 

The probe reaction utilized a 1/1 molar mixture of methanol and isobutanol over H-mordenite, a strongly acidic zeolite comprised of linear one-dimensional channels made up of 12-ring 6.5 by 7.0 A windows [8]. There is a side-pocket system in H-... 

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