Enantiomerically Pure trans-3,4-Disubstituted Tetrahydrothiophenes from Diastereoselective Thiocarbonyl Ylide Addition to Chiral α,β-Unsaturated Amides

Abstract

Asymmetric 1,3-dipolar cycloadditions of a sulfur-containing 1,3-dipole and α,β-unsaturated camphorsultam amides as dipolarophiles are described. The cycloaddition products, trans-3,4-disubstituted tetrahydrothiophenes, were obtained in high diastereomeric ratios (up to 90:10) and in high yields. Chromatographic removal of the minor diastereomer followed by cleavage of the chiral auxiliary furnished either the enantiomerically pure corresponding alcohol or carboxylic acid.

Pheromones of Pine Sawflies: Synthesis of a Pure (2S,3R)-3-Methylalkan-2-ol Stereoisomer via an Asymmetric 1,3-Dipolar Cycloaddition; Preparation of a Pheromone Component of Macrodiprion nemoralis

“…14 Thus trans-3,4-disubstituted tetrahydrothiophene derivatives are accessible as pure enantiomers via a simple sequence. 14 We have also demonstrated that an a,b-unsaturated dipolarophile containing a b-benzyloxy group functions well as the reactive partner in this cycloaddition sequence (cf. Scheme 2).…”

“…Scheme 2). 14 The resulting 3-tetrahydrothienylcarboxamide contains a trans-4-oxygen substituent. It occurred to us that such tetrahydrothiophenes could be used as building blocks for the construction of enantiopure threo-3-methylalkan-2ols after desulfurisation and debenzylation via a simple synthetic sequence.…”

Preparation and Odour Properties of (S)-3-Mercapto-1-Heptyl Acetate

“…The NMR data were consistent with those described in the literature. 22 Methyl (E)-2-heptenoate 2: To a solution of (E)-2-heptenoic acid 1 (32 g, 0.25 mol) in methanol (120 mL) was added SOCl 2 (35.7 g, 0.3 mol) dropwise. The mixture was then heated to reflux for 4 h. Most of the methanol and excess SOCl 2 were removed by rotary evaporation.…”

Use of 1,3-dipolar reactions for the preparation of SF5-substituted five-membered ring heterocycles. Pyrroles and thiophenes

“…Chloromethyl trimethylsilylmethyl sulfide was first devised and used as a parent thiocarbonyl ylide synthon by Sakurai in 1986 [23,24], being utilized to prepare di-and tetrahydrothiophenes via 1,3-dipolar cycloadditions by treatment with CsF in acetonitrile in the presence of appropriate dipolarophiles [25]. Indeed, when various SF 5 -aryl-substituted alkynes were used as substrates, the cycloadditions proceeded smoothly to form the respective dihydrothiophenes, 10a, c and d (Scheme 8).…”