C-Chain extension

Application of the previously described reaction sequence allows an initial insertion reaction with dichloromethyllithium to give 20 Then 20 is enhanced by one C, residue using Grignard reagent 21 to produce 22. Another reaction with dichloromethyllithium results in a C chain extension to product 5. Since the insertion reaction with dichloromethyllithium was conducted twice, the distance between the boron atom and the PMB ether inemases by two carbon atoms. 

Ying et al. also synthesized block copolymers of MMA and HEMA using ATRP methodologies [186]. The polymerizations also invoked the halogen exchange [175] by using an ethyl 2-bromopropionate/CuCl/bpy catalyst system and acetonitrile as a polymerization medium. The authors found that the polymerization of MMA could be controlled at 40 °C, while for the ATRP of HEMA, the temperature could be lowered to 20 °C. Chain extension of a lower molecular... 

Scheme 8.9. Reagent-controlled synthesis of L-allose ((+)-AE = Sharpless AE using L-(+)-DIPT (-)-AE = Sharpless AE using d-(-)-DIPT). (a) A Sharpless AE followed by Payne rearrangement and oxidation, (b) Stereodifferentiation of the C-4 and C-5 stereocenters, (c) Chain extension followed by reagent-controlled oxidation of the olefin, (d) Completion of the synthesis.

Synthesis (s. a. C-Chain extension. Condensation, Friedel-Crafts ketone synthesis, Oxalic ester -)... 

Ethylenealdehydes from 2-(r-alkenyl)cycloalkanols—C-Chain extension s. 16, 213... 

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