An Unusual Pathway to Cyclobutane Formation via Desulfurative Intramolecular Photocycloaddition of an Enone Benzothiazoline Pair
作者:Hyunil Jo、Mark E. Fitzgerald、Jeffrey D. Winkler
DOI:10.1021/ol900186y
日期:2009.4.16
Irradiation of the enone benzothiazoline 3 leads to the formation of cyclobutane 5. Preliminary mechanistic studies establish the intermediacy of an enecarbamate 14 in this photochemical transformation, which could be the result of sulfur extrusion from an episulfide intermediate. Photocycloaddition of the enecarbamate intermediate 14 leads to the formation of “crossed” photoadducts, i.e., 5, in excellent
Selectivity Reversal during Thia-Michael Additions Using Tetrabutylammonium Hydroxide: Operationally Simple and Extremely High Turnover
作者:Daniel Nicponski、Jennifer Marchi
DOI:10.1055/s-0033-1341106
日期:——
The use of tetrabutylammonium hydroxide as a novel and exceedingly efficient thia-Michael addition catalyst is herein described. This extremely simple methodology allows for the conjugate addition of a wide variety of mercaptan nucleophiles, and functions remarkably well with a very wide range of both classical and non-classical Michael acceptors. Contradistinctive to current literature reports, the use of this catalyst more efficiently promotes the addition of more basic thiols. This methodology is especially attractive and operationally simple, as it generally proceeds with only 1 mol% catalytic loading and without excess reagent, and the produced products typically require no purification.
Photochemical Route to the Synthesis of Thiolane 1-Oxides
作者:Jeffrey D. Winkler、Esther C. Y. Lee
DOI:10.1021/ja060962r
日期:2006.7.19
The preparation of thiolane 1-oxide 10 by photochemically mediated rearrangement of sulfoxide 9 in high yield is described. The efficient construction of quaternary carbon centers underscores the utility of this methodology in organic synthesis. Further manipulation of photoadduct 10 leads to the formation of diverse heterocyclic structures.