Synthesis of 4‐heterocyclyl‐hexahydro‐8‐methoxyfuro[3,2‐c]quinolines by Lewis acid catalyzed [4 + 2]cycloaddition reaction

Abstract

Synthesis of 2-substituted quinoline derivatives by Lewis acid catalyzed [4 + 2]cycloaddition was investigated.

Preparations of Trisubstituted Hydrazines and Pyrazolidines from N-(1-Benzotriazolylalkyl)hydrazines

“…Treatment of 2a with cyclic vinyl ethers gave cis -fused bicyclic compounds 5a and 5b exclusively; the cis relationship of H-3 and H-4 was determined by NOE experiments and the coupling H-3/H-4 constants in the 1 H NMR. These are 6.1 Hz for 5a and 1.7 Hz for 5b , consistant with literature reports − for furan five:five and five:six ring system, respectively. Similarly 2e was reacted with vinyl ethyl ether and 3,4-dihydropyran under similar conditions to give good yields of the expected cyclic pyrazolines 4c and 5c , respectively.…”

Simple 1,2‐Diamine Ligands for Asymmetric Addition of Aryllithium Reagents to Imines

“…Other commercially available reagents were used without further purification, unless otherwise indicated. Imines 2 ,9 5 ,15 8 ,9 9a ,16 9b ,17 9c ,18 9d ,19 9e ,20 9f , 10 ,21 and 11 ,22 were generated by condensation of p ‐anisidine with the corresponding aldehyde. Ligands 1b – f ,8 7a ,12 7c 12 and 7b 13 were synthesized as described in the literature.…”

Thiazolidine-2-thione Directed Diastereoselective Addition of Chlorotitanium Enolates to Aldimines

“…These compounds were synthesized following the literature procedures. 21,22 Imines 2i-2viii These compounds were prepared following the literature procedure. 24…”

“…Surprisingly, the observed anti/syn-product ratios exhibited only small variations as the reaction temperatures were changed from -78 to 0 °C. The addition of titanium enolates of 3a to imines 1ii and 1iii derived from several heteroaromatic aldehydes [21][22][23] proceeded with a similar stereochemical outcome as for imine 1i. Although the isolated yields are considerably lower, imines derived from 2-furylaldehyde (1ii) and 2-thienylaldehyde (1iii) also produced the anti-product as the major isomer at low temperature (Table 1).…”