Microwave-assisted selective protection of glutaraldehyde and its symmetrical derivatives as monoacetals and -thioacetals

Six monoprotected acetals and -thioacetals of glutaradehyde and its symmetrical dimethyl derivatives were synthesized. Microwave-assisted heating proved to be a substantially more selective method for monoprotection than conventional heating. All reactions were efficient and only traces of diprotected material were formed.     

Out-diffusion and precipitation of copper in silicon: An electrostatic model

Concentrations of mobile interstitial copper and precipitated copper in silicon were studied after a high temperature intentional contamination and quench to room temperature. It was found that below a critical contamination the copper predominantly diffuses out to the surface, while for higher initial copper concentrations it mainly precipitates in the bulk. The critical copper contamination equals the acceptor concentration plus 10(16) cm (-3). This behavior can be explained by the electrostatic interaction between the positively charged interstitial copper and the forming copper precipitates.     

Microwave-assisted total synthesis of tangutorine

A novel microwave approach to the synthesis of tangutorine is described. The key steps comprise a diastereoselective aldol condensation of monoprotected glutaraldehyde and a microwave-assisted Pictet–Spengler reaction. The stereochemistry of the tangutorine diastereomers obtained was determined by means of NOE-experiments.