Unexpected behavior of dienol thio ethers gives versatile access to a large set of functionalized dienes

Scope and Limitations of the Domino Vinylogous Aldol/oxa‐Michael Reaction

“… Synthesis of α,β ‐unsaturated aldehydes bearing a sulfide moiety. Reactions (a), (b), (d) and (e) have been reported in the literature . Reagents and conditions : (a) NEt 3 , PhSH, Et 2 O, r.t., 8 h, 83 %; (b) 2 m HCl, acetone, r.t., 4 h, 65 %; (c) NEt 3 , 4‐CH 3 OPhSH, Et 2 O, r.t., 8 h, 54 %; acetal cleavage occurred during substitution reaction; (d) NaOEt, EtSH, Et 2 O, r.t., 12 h, 76 %; (e) HCO 2 H, acetone, r.t., 4 h, 47 %; (f) NEt 3 , 4‐NO 2 PhSH, Et 2 O, 20 °C, 12 h, 39 %; (g) 2 m HCl, acetone, r.t., 4 h, 96 %.…”

“…We initiated our studies with the synthesis of various α,β ‐unsaturated aldehydes in order to get a wide substrate spectrum. In this respect, starting from 3‐methyl‐2‐butenal 7 , bromide 9 was synthesized in two steps according to a procedure by Duhamel et al . (Scheme ).…”

“… Synthesis of bromide 9 . Reagents and conditions : (a) Si(CH 3 ) 3 Cl, ZnCl 2 , NEt 3 , Et 2 O, reflux, 2 d, 52 %; (b) Br 2 , MeOH, DMF, –20 °C, 4 h, 85 %.…”

Stereoselective synthesis of cyclic amino acidsvia asymmetric phase-transfer catalytic alkylation

“…Glycine t-butyl ester-benzophenoneimine Schiff base 1, 11 alanine t-butyl ester-p-chlorobenzaldimine Schiff base 6, 12 chiral phase transfer catalysts (S)-2a, (S)-2b and (S)-2c were prepared according to the literature procedure. 6b Alkyl halides 3, 13-15 8 13 and 13 16 were prepared according to the literature procedure. Cyclic amino esters 5b, 17 5d, 18 5a, 8a 10e 9 and 10f 9 are known compounds.…”

“…Daicel Chiralpak AS-H, hexane/2-propanol = 10/1, flow rate 1.0 mL min −1 , λ = 254 nm, retention time: 16 …”