Prescriptive Durability Specification

A specification that defines required results, criteria by which performance will be judged, and methods of evaluation, without requirements for how the results are to be obtained

Application examples of performance-based specification and quality control

This chapter presents an overview on several performance-based approaches for concrete durability specification and conformity assessment of the as-built structure.

Aza-annulation of enaminones with crotonyl chloride - Formal reversal of regioselectivity.

The regiochemistry of aza-annulation of enaminones with alpha,beta-unsaturated acid chlorides bearing hydrogen atoms on the gamma-carbon is reversed when triethylamine is used as mediator. When the reaction was carried out at lower temperatures as 3-acyl beta,gamma-unsaturated compound could be isolated which cyclised to the desired product under thermal or basic conditions. The nature of this intermediate strongly suggests that a vinyl ketene is the active acylating agent. (C) 1997 Elsevier Science Ltd.