Organolithium-mediated cyclization reactions: a practical way to access hetero- and carbocycles

Abstract

Cyclization reactions are considered as one of the most important reactions in organic synthesis due to the fact that natural molecules contain cyclic components either as part of the molecule or molecular skeleton.

Recycling and environmental issues of lithium-ion batteries: Advances, challenges and opportunities

“…Lithium is also important in other applications, including medicine and metallurgy. For instance, the chemical industry uses it to decrease the viscosity of glass and ceramic [24], as desiccants for gas streams [25], to strength alloys [26], as base and nucleophile (organolithium) [27] and as a lubricant in automotive applications [28]. In medicine, lithium is used in the treatment of bipolar disorder [29], depression [30] , dental [31] and headaches [32].…”

Formal Synthesis of ent-Cephalotaxine Using a One-Pot Parham–Aldol Sequence

“…7 Instead of forming this enolate 6 from the parent diketone, we considered expelling the enolate from exo-butenolide 7 following a Parham cyclization to initially form the ring B. 8 We recently disclosed an asymmetric Lewis acid mediated [1,2]-Stevens rearrangement of proline-derived benzyl derivatives of the type 10, which afforded corresponding quaternary α-benzyl proline derivatives 11 in good to excellent yields (62-85%) and high enantiomeric purity (er >98:2) ( Figure 2, b). 9 We speculated that N-allyl prolineamide 12 might also be a competent substrate for this reaction, and result in α-allyl prolineamide 9 (Figure 2, b).…”

“…(R (8). A beige suspension of amine 9 (294 mg, 1.90 mmol, 1.00 equiv), nosylate 16 (1.0 g, 2.1 mmol, 1.2 equiv), 24 and K 2 CO 3 (790 mg, 5.70 mmol, 3.00 equiv) in acetonitrile (10 mL) was refluxed for 13 h. The resulting mixture was cooled to rt and filtered through a fritted funnel, and the filter cake was washed with thoroughly with EtOAc (3 × 3 mL).…”

“…Ring D of enone 5 is known to form in an intramolecular aldol condensation of enolate intermediate 6 . Instead of forming this enolate 6 from the parent diketone, we considered expelling the enolate from exo -butenolide 7 following a Parham cyclization to initially form ring B . Such a protocol would allow for forging both rings B and D in a single operation by lithiation of intermediate 7 .…”

“…7 Instead of forming this enolate 6 from the parent diketone, we considered expelling the enolate from exobutenolide 7 following a Parham cyclization to initially form ring B. 8 Such a protocol would allow for forging both rings B and D in a single operation by lithiation of intermediate 7. To construct the needed precursor 7, we considered iodolactonizing amide 8, which can be derived from α-allylated prolineamide derivative 9.…”