Synthesis and Asymmetric Diels−Alder Reactions of Enantiopure 3-(Alkylsulfinyl)-1-methoxy-1,3-butadienes

Abstract

Simple syntheses of enantiopure (E)- and (Z)-3-(alkylsulfinyl)-1-methoxy-1,3-butadienes 2and 3 were provided by the addition of (1S)-isoborneol-10-sulfenic and (S)-phenyl-2-hydroxyethanesulfenic acids 8 to (E)- and (Z)-1-methoxybut-1-en-3-ynes (9) and (10). These additions proceeded with asymmetric induction, the extent of which depended upon the nature of the chiral hydroxyalkyl group. Cycloadditions of methyl acrylate to the enantiopure dienes proceeded with complete regioselectivity and very high stereoselectivity when catalyzed by lithium perchlorate or zinc chloride in dichloromethane. The chirality at sulfur controlled the diastereofacial selectivity in these Diels-Alder cycloadditions.

Efficient Synthesis of Unsymmetrical Disulfides through Sulfenic Acids

“…The synthetic strategy is illustrated in Scheme and the results are shown in Table 1. Two steps were required to convert thiols 1a , b into sulfinyl precursors 6 – 9 of the corresponding sulfenic acids 10a , b , through sulfides 2 – 5 12a,12b,12e,12h. Thermolysis of sulfoxides 6 – 9 that generate transient sulfenic acids 10a , b was performed in the presence of thiols 11b – h and 1,3‐benzenedithiol ( 21 ) with an almost 2:1 sulfoxide/thiol group ratio (Table 1).…”

“…During the last decade, we have gained expertise in the choice and preparation of sulfenic acid precursors 12b,12h,13. Entries 2–4 in Table 1 show how the use of sulfoxides 6 – 8 , as precursors of sulfenic acid 10a , in the presence of thiol 11c , allows the formation of disulfide 12 under different reaction conditions but always in excellent yields.…”

Regio‐ and Stereocontrolled Synthesis of (Z)‐α‐(Phenylseleno)sulfinyl and ‐sulfonyl Alkenes via Sulfenic Acids, and a Study of their Reactivity

“…13 C NMR spectra were acquired by the APT technique. Heteronuclear single quantum coherence and NOESY experiments were also performed for several compounds.…”

“…[12] Enantiopure sulfenic acids can be generated from suitable enantiopure sulfinyl precursors and their addition to unsaturated bonds produces diastereomeric mixtures of sulfoxides that can usually be separated by simple column chromatography. [13] We have used this route to obtain optically pure active derivatives. Furthermore, the reactivity of such electron-poor alkenes has been exploited and discussed with regard to accessing substituted vinyl sulfoxides with controlled stereochemistry at the double bond.…”

Highly Regio- and Stereoselective Synthesis of (1Z,3E)-2-sulfonyl-3-stannyl-1,3-dienes by hydrostannylation of (Z)-2-sulfonyl-1,3-enynes

“…[13][14][15][16][17][18] In addition, difunctionalised 1,3-dienes containing a heteroatom can control reactions both regio-and stereoselectivity and play a very important role in cycloadditions. [19][20][21][22] Jin and co-workers reported the stereoselective synthesis of 2-alkoxy-3-alkyl(aryl) thiobuta-1,3-dienes by a Negishi coupling reaction between an α-alkyl(aryl)thio vinyl zinc chloride and α-bromo vinyl ether. 23 Coleman and Walczak reported the stereoselective synthesis of (E,E)-1-tributylstannyl-4-borylbuta-1,3-diene and its use as an orthogonal Stille and Suzuki-Miyaura coupling partner.…”