[33462-38-3] · C6H10CuLi · Lithium Di-(E)-1-propenylcuprate · (MW 152.65)
Solubility: sol Et2O, THF.
Preparative Methods: prepared in situ from CuI salts (Copper(I) Iodide)7 or complexes (Copper(I) Iodide-Tributylphosphine5,9 and Copper(I) Iodide-Trimethyl Phosphite4) in Et2O or THF at -78 °C under argon1c by the addition of trans-1-propenyllithium.7 See Lithium Dimethylcuprate for purification of CuI salts.
Handling, Storage, and Precautions: air- and moisture-sensitive; use in a fume hood.
Lithium di-(E)-1-propenylcuprate displays the typical reactivity patterns of lithium diorganocuprates (see Lithium Dimethylcuprate).
Lithium di-(E)-1-propenylcuprate undergoes 1,4-addition to simple a,b-alkenyl ketones2 with retention of alkene configuration by conjugate transfer of the (E)-1- propenyl ligand. This reaction has been applied to the synthesis of (±)-dechloromycorrhizin A (eq 1).10 1,4-Additions have been achieved with ethyl acrylate and ethyl propiolate in limited yields.4 In the synthesis of aucantene, 1,4-addition to an a,b-alkenyl aldehyde3 was achieved (eq 2). Diastereoselective 1,2-additions of lithium di-(E)-1-propenylcuprate to aldehydes can be performed in good yields5 and in the presence of Magnesium Bromide etherate, which facilitates chelation control (eq 3).6
Lithium di-(E)-1-propenylcuprate reacts with alkyl halides and tosylates in high-yield substitution reactions, with and without HMPA additive, in Et2O or THF.7 Coupling of lithium di-(E)-1-propenylcuprate with a vinyl chloride was used in the synthesis of fulvoplumieren (eq 4).8
Oxidative dimerization of a copper(I) ate complex prepared from trans-1-propenyllithium affords a good yield of the dimer trans,trans-2,4-hexadiene, without loss of stereochemical integrity (eq 5).9
Christopher W. Alexander & R. Karl Dieter
Clemson University, SC, USA