N-BuLi

Homoallyl alcohol (3) Metalation of (E) butene (1 05 equiv) with n BuLI (t equiv) and KOtBu (1 equiv) in THF at SO C for 15 mm followed by treatment of (E)-crotyl potassum salt with B(OiPr)3 at 79°C gave after quenching with 1 N HCI and extraction with EtjO containing 1 equiv of diisopropyl tartarate. the crotyl boronate 2 A solution of decanall (156 mg 1 mmol) was added to a toluene solution of 2 (1 1 15 equiv) (0 2 M) at 78 C containing 4A molecular sieves (15-20 mg/L) After 3 h at -78°1 N NaOH was added, followed by extraction and chromatography to afford 208 mg of 3 (90%), anti syn 99 1... 

The nitrobenzyl caibonates were prepared to protect a secondary hydroxyl group in a thienamycin precursor. The o-nitrobenzyl carbonate was prepared from the chloroformate (DMAP, CH2CI2, 0° - 20°, 3 h) and cleaved by irradiation, pH 7. The p-nitrobenzyl carbonate was prepared from the chloroformate (—78°, n-BuLi, THE, 85% yield) and cleaved by hydrogenolysis (H2/Pd-C, dioxane, H2O, EtOH, K2HP04). It is also cleaved by electrolytic reduction. ... 

KOH, H2O, reflux, 12 h, 64-92% yield. This group is more stable to n-BuLi than is the benzyl group when used to protect imidazoles. 

Pyrroles and indoles can be protected with the r-butyldimethylsilyl group by treatment with TBDMSCl and n-BuLi or NaH. Triisopropylsilyl chloride (NaH, DMF, 0°-rt, 73% yield) has been used to protect the pyrrole nitrogen in order to direct electrophilic attack to the 3-position.It has also been used to protect an indole.This derivative can be prepared from the silyl chloride and The silyl protective group is cleaved with Bu4N F , THF, rt or with CF3COOH. 

Fig. 7.2. Crystal structures of n-butyllithium. (A) (n-BuLi TMEDA)2 (B) (n-BuLi THF)4 hexane (C) [n-BuLi DME4] (D) [(n-BuLi TMEDA]. Hydrogen atoms have been omitted. (RcprcvJuccd from./ Am. Chem. Soc., 115, 1568, 1873 (1993).

Crystal structure determination has also been done with -butyllithium. A 4 1 n-BuLi TMEDA complex is a tetramer accommodating two TMEDA molecules, which, rather than chelating a lithium, link the tetrameric units. The 2 2 -BuLi TMEDA complex has a structure similar to that of [PhLi]2 [TMEDA]2. Both 1 1 -BuLi THF and 1 1 -BuLi DME complexes are tetrameric with ether molecules coordinated at each lithium (Fig. 7.2). These and many other organolithium structures have been compared in a review of this topic. ... 

---