Building block approach, construction

This reaction is particularly suitable for the preparation of the Wieland-Miescher ketone 96, a very useful building block for construction of a broad variety of biologically active compounds such as steroids, terpenoids, and taxol. On the basis of the proline-catalyzed approach described above Barbas et al. recently reported an optimized procedure for formation of the chiral Wieland-Miescher ketone, 96 [105]. It has been shown that this synthesis (which comprises three reactions) can be performed as a one-pot synthesis. The desired product is obtained in 49% yield with enantioselectivity of 76% ee (Scheme 6.43). Here L-proline functions as an efficient catalyst for all three reaction steps (Michael-addition, cydiza-tion, dehydration). It is also worth noting that although many other amino adds and derivatives thereof were tested as potential alternative catalysts, L-proline had the best catalytic properties for synthesis of 96. This result emphasizes the superior catalytic properties of proline reported after previous comparative studies by the Hajos group [100, 101]. 

The construction of such compounds via stepwise building-block approaches, as in the synthesis of the hexadecker sandwiches21 in Fig. 5-22, lends order and controllability to this area, and may allow the rational development of new materials having desired combinations of electronic, magnetic, optical, or other properties. 

Abbott compares SAR by NMR to combinatorial chemistry as follows Both methods use a building block approach in the construction of molecules however, in combinatorial chemistry, thousands to millions of molecules are typically synthesized and tested for activity. In SAR by NMR, less than 10 molecules is required because the chemistry is highly focused on linking molecules demonstrated to bind to the protein target using structural information on how they interact. Patent applications have been filed on the method, but the company plans to make the technology available to other drug developers. 

C., and Moeller, K. D. (1998) Thyrotropin releasing hormone analogs A building block approach to the construction of tetracyclic peptidomimetics. Bioorg. Med. Chem. Lett. 8, 3093-3096. 

Scarp tires have retaining strength and flexibility characteristics that make them potentially attractive as a basic construction material. They are relatively small and easy to handle, and their geometric configuration lends itself to a building block approach in constructing larger modules. 

The building block approach is one of the procedures for rational construction of higher-order structures of inorganic materials at the nanometer level. In this procedure, compounds with well-defined structures such as clusters are usually used as starting materials and cross-linking reactions of such compounds are carried out to build up frameworks of the materials. Production of materials with structures as desired will be possible on the condition that the arrangement and cross-linking of the compounds will have been controllable. 

In order to provide some kind of structure to what could be very complex control systems, there exists a need for a suitable system decomposition technique. Object oriented techniques provide one possible approach to providing the main structuring element of the CBASS environment. Object Oriented techniques offer support for a highly modular structure which supports a building block approach to control svstem construction. 

---