Synthesis of 12-Membered and 13-Membered Sulfur-Containing Lactones by Homolytic Macrocyclization of Mercaptoacetic Esters with Alkynes

Starting from mercaptoacetic acid esters of 1,2- or 1,3-diols and substituted acetylenes 12- and 13-membered sulfur-containing lactones as 1:1 adducts were synthesized in yields up to 48%. The mechanism of this homolytic reaction, which is initiated by the tripropylborane/oxygen system, includes generation of thiyl radicals and their addition to the triple bond of alkynes

Homolytic cycloaddition of dithiols to alkynes leading to sulfur-containing heterocycles and crown thioethers: new comments to the mechanism

Multicenter three-electron (3e-2c) S-S bond formation can be employed to explain the cyclization in the homolytic addn. of α,ω-thiols to alkynes

An Approach to 8-Membered, 16-Membered and 24-Membered Sulfur- Containing Heterocycles Via Homolytic Cycloaddition of Alkynes with Butane-1,4-Dithiol

Homolytic cycloaddition of butane-1,4-dithiol with alkynes offers a facile one-pot route to 8-membered 1,4-dithiocanes and 16-and 24-membered crown thioethers, 1,4,9,12-tetrathiacyclohexadecanes and 1,4,9,12,17,20-hexathiacyclotetracosanes

Synthesis of 12- and 13-Membered Sulfur-Containing Lactones by Homolytic Macrocyclization of Mercaptoacetic Esters with Alkynes

Starting from mercaptoacetic acid esters of 1,2- or 1,3-diols and substituted acetylenes 12- and 13-membered sulfur-containing lactones as 1:1 adducts were synthesized in yields up to 48%. The mechanism of this homolytic reaction, which is initiated by the tripropylborane/oxygen system, includes generation of thiyl radicals and their addition to the triple bond of alkynes

Stereoselective Free-Radical Cycloaddition-Macrocyclization in Facile Synthesis of Trans-Cyclohexano-Fused 12-Membered Crown Thioethers

Homolytic cycloaddition of dithiols 1,2 derived from trans- and eis-1,2-cyclohexanediols to alkynes, induced by Pr3B-O2, offers an extremely simple approach to trans- and cis-cyclohexano-fused 12-membered crown thialactones 4a-c-7a-c. The reaction of trans-1 proceeds with pronounced remote 1,6-asymmetric induction to give predominantly (IS *, 6R *, 12S *)-4a–c, while cis-2 reacts nonstereoselectively. Basing on molecular mechanics calculations the stereoselectivity is rationalized as a result of entropy favored pathway of macrocyclization

Remote Asymmetric Induction in Free-Radical Cycloaddition Leading to Trans-Cyclohexano-Fused 12-Membered Crown Thioethers

Homolytic cycloaddition of dithiol 1, derived from trans-1,2-cyclohexanediol, to alkynes induced by Pr3BO2 occurs with 1,6-asymmetric induction to afford predominantly (1S∗, 6R∗, 12S∗)-trans-cyclohexano-fused 12-membered crown thialactones 4a-c. No pronounced diasteroselectivity was found in the corresponding reactions of dithiol 2, derived from cis-1,2-cyclohexanediol

Stereoselective Free Radical Cycloaddition-macrocyclization in Facile Synthesis of \u3cem\u3etrans\u3c/em\u3e-cyclohexano-fused 12-membered Crown Thioethers

Homolytic cycloaddition of dithiols 1,2 derived from trans- and eis-1,2-cyclohexanediols to alkynes, induced by Pr3B-O2, offers an extremely simple approach to trans- and cis-cyclohexano-fused 12-membered crown thialactones 4a-c-7a-c. The reaction of trans-1 proceeds with pronounced remote 1,6-asymmetric induction to give predominantly (IS *, 6R *, 12S *)-4a–c, while cis-2 reacts nonstereoselectively. Basing on molecular mechanics calculations the stereoselectivity is rationalized as a result of entropy favored pathway of macrocyclization

Solvent effects on C=O stretching frequencies of some 1-substituted 2-pyrrolidinones

In an effort to model solute–solvent interactions, the C=O stretching frequencies of five 1-substituted 2-pyrrolidinones and four other carbonyl-containing compounds were measured for 30 common solvents. These were then correlated with four empirical parameter sets and one theoretical (computational) parameter set. While an empirical parameter set gave the best correlation equations, the theoretical parameter equations are physically and statistically significant. Solvent volume, polarizability and hydrogen bond donor acidity (capacity) terms are significant in the correlation equations.