Telescopic route

Telescoping, selecting reagents, and reaction optimization can afford significant decreases in the COG. The process route initially used to prepare 200 kg of the API intermediate acid 44 involved seven steps, four solvents, bromination, diazotization, and reaction with CO at 120°C, and produced the drug candidate in 20% yield. The optimized route shown in Scheme 2.12 was operationally simpler (using the same vessel for every... 

One of the most widely used methods to improve overall process efficiency is to reduce the number of steps and unit operations in a synthetic route. This is more commonly known as telescoping. This can lead to more efficient, less wasteful processes that require fewer solvents because of the smaller number of steps. An example of this technique was illustrated earlier in Section 3.1.6, where the process optimization of the sertraline (Zoloft ) production process by Pfizer was described. In this case the number of process steps (unit operations) was reduced from 3 to 1, which led to huge savings due to higher productivity, fewer inputs, and less waste generation [18]. 

As with the ozonolysis route, this single-pot approach telescopes via sequential hydrogenation, dehydration, reduction, and basic lactam cyclization chemistry. Although... 

One solution is to use a telescopic technique with progressively larger sizes to enlarge the costoclavicular route. Therefore, because the subclavian vein is compressed between the clavicle and anterior scalene muscle when the shoulder is displaced posteriorly and downward, it is advantageous to have the shoulder in neutral position with no roll during sheath advancement to keep the vein wide open. When sheath advancement is not possible or unsuccessful despite using the telescopic technique, and if the lead is free from adhesions, the Pisa approach [32] may be helpful. 

Carrying the plasterboard through a stairway was not the normal procedure, the other boards were hfted earlier to the third floor with a telescopic handler, but this option was not available anymore. In any case, the stairway was used as the main route to the third floor. Closing the access during the handrail installation work would have been the absolute correct thing to do. 

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