[84531-04-4] · C4H5Li · 1,3-Butadienyl-2-lithium · (MW 60.02)
Preparative Methods: 1,3-butadienyl-2-lithium is synthesized by transmetalation of 1,2-butadienyl-2-tributyltin (eq 1)1 or by the Shapiro reaction of 2,4,6-(i-Pr)3C6H2SO2NHN=CMeCH=CH2 with Methyllithium (eq 2).2 3-Methyl-1,3-butadienyl-2-lithium has been prepared by lithium-bromine exchange.5.
Analysis of Reagent Purity: 1,3-butadienyl-2-lithium is synthesized and used direclty without further isolation or purification.
Handling, Storage, and Precautions: use in a fume hood.
1,3-Butadienyl-2-lithium reacts with aldehydes and ketones. Dienyl carbinols are generally obtained as major products, along with small amounts of allenyl carbinols (eq 3). Compared with 1,3-Butadienyl-2-magnesium Chloride, a stronger preference for dienyl products is observed (Table 1).1
1,3-Butadienyl-2-lithium undergoes Michael addition to a,b-alkenyl esters. The reaction with methyl 2-(trimethylsilyl)propenoate affords the corresponding lithium enolate, which upon alkylation yields a series of a-silyl esters (eq 4).3
Treatment of the Michael adduct with an aldehyde followed by Peterson alkenation furnishes the dienyl a,b-alkenyl ester (eq 5).4 Stereoselectivities of the products vary with the substrate (E/Z = ca. 3:1 to Z only).4
Substituted 2-lithiobutadienes which have been prepared include 3-methyl-,5 3-trimethylstannyl-,6 3-trimethylsilyl-,6 3-hexyl-,6 and 4-methoxy-1,3-butadienes.7
Yusuke Kawakami & Atsunori Mori
Japan Advanced Institute of Science & Technology, Ishikawa, Japan
Toyama National College of Technology, Japan