Precursors next-generation applications

Polysilylenes have been widely investigated in the past decade because of their potential applications in the field of materials science [1], Recent applications of polysilylenes in SiC precursors [2], microlithography [3], photoinitiators [4], and reprography [5] show that polysilylenes are very promising as advanced materials for high technology of the next generation. 

Based on this approach, families of silicon carbide fiber and silicon ceramic composites are now being routinely produced based on polycarbosilane precursors [22] These new materials are finding a wide range of new applications, for example, as a hot zone component in the next generation turbojets where silicon carbide composite components now routinely service at operating temperatures well in excess of 1000°C under high static thrusts (up to 50,000 psi) and high sonic pressure (up to 800 DB). No metallic components survive under these conditions. 

Sequences of disconnections can be built by the CHAOSBASE program, analogous to those included in the CHAOS program. If CHAOS finds a sequence included in a data base, applicable to the target molecule, a dialog box will come up, which is very similar to the one in the last figure but also contains the buttons Last and Next. These buttons allow you to see the various intermediate precursors generated in the sequence. 

In addition to utilizing the heterocycloreversion of 2-azanorbomenes as an aqueous deprotection protocol for primary amines, where the formation of the transient iminium ion is incidental, 2-azanorbomene derivatives can also serve as precursors to iminium ions with the intention of synthetically exploiting these unstable intermediates. Such heterocycloreversion applications do not involve the use of aqueous media to avoid undesired hydrolysis of the newly generated iminium ion. The next few examples illustrate the use of 2-azanorbomenes as iminium-ion synthons unmasked by the reverse Diels-Alder process (see section 2.4.1). 

---