[58384-88-6] · C15H21CuLi2 · Dilithium Tris(1-pentynyl)cuprate · (MW 278.79)
Solubility: sol ether to -78 °C.
Preparative Method: to purified Copper(I) Iodide (10.5 mmol) suspended in ether at 0 °C is added 1-pentynyllithium (30 mmol; prepared from n-Butyllithium and 1-pentyne).3
Handling, Storage, and Precautions: should be used immediately following preparation.
Li2Cu(1-pentynyl)3, in ether with HMPA as cosolvent, adds regiospecifically to cyclic enones to produce 1,2-alkylation products in high (85-95%) yield (eq 1).1 Li2Cu(1-pentynyl)3, as well as other dilithium trialkynylcuprates, failed to give 1,2- or 1,4-addition products in ether alone.3,4
1-Pentynylamines are formed by displacement of electrophilic amines with Li2Cu(1-pentynyl)3 in 69-87% yield (eq 2) depending on the amine substrate and the conditions used in the preparation of Li2Cu(1-pentynyl)3.2 For example, formation of Li2Cu(1-pentynyl)3 from 3 equiv of 1-pentynyllithium and 1 equiv of Copper(I) Cyanide resulted in a 69% yield, while forming Li2Cu(1-pentynyl)3 from 3 equiv of 1-pentynyllithium and 1 equiv of CuBr.DMS (see Copper(I) Bromide) gave an 87% yield using the same electrophilic amine.
Timothy J. Guzi & Timothy L. Macdonald
University of Virginia, Charlottesville, VA, USA