- A Spiroalkylation Method for the Stereoselective Construction of α-Quaternary Carbons and Its Application to the Total Synthesis of (R)-Puraquinonic Acid
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Cyclic α-quaternary carbon stereocenters were prepared from biselectrophillic substrates and an easily prepared chiral bicyclic sulfonyl lactam. This was achieved in two steps by spiroalkylation, employing biphasic reaction conditions with a phase-transfer catalyst, followed by reduction and alkylation with a series of alkyl halide electrophiles. The products of this method were isolated in good yields with with high levels of diastereoselectivity. This methodology was employed in the enantioselective total synthesis of (R)-puraquinonic acid (1) for a late-stage installation of the α-quaternary carbon stereocenter. This enabled the shortest synthesis of 1 to date, an eight-pot sequence providing an overall yield of 14%.
- Elmehriki, Adam A. H.,Gleason, James L.
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supporting information
p. 9729 - 9733
(2019/12/02)
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- NOVEL COMPOUNDS FOR MODULATION OF ROR-GAMMA ACTIVITY
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The present invention relates to aryl sulfones and related compounds that are modulators of ROR-gamma receptors. The invention also provides pharmaceutical compositions comprising these modulators, and methods of modulating ROR-gamma receptors using them. Also provided are methods of using aryl sulfones and related compounds as modulators of ROR-gamma to treat ROR-gamma mediated diseases
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- The regiochemistry of cyclization of α-sulfenyl-, α-sulfinyl-, and α-sulfonyl-5-hexenyl radicals: Procedures leading to regioselective syntheses of cyclic sulfones and sulfoxides
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A study of the cyclization of α-sulfenyl-, α-sulfinyl-, and α-sulfonyl-5-hexenyl and 5-methyl-5-hexenyl radicals reveals a unique contrast in the mode of ring closure of the radicals. In the case of the 5-hexenyl radicals, the sulfinyl-substituted species displays unexpected regioselectivity relative to its analogues. Thus, while the α-S- and α-SO2-5-hexenyl radicals give measurable and increasing quantities of 6-endo product, the α-sulfinyl species cyclizes with high selectivity (95.5:4.5) via a 5-exo mode. By contrast, ring closure of the 5-methyl-5-hexenyl radicals is found to give substantially the 6-endo product in all cases. It is the α-sulfonyl-5-methyl-5-hexenyl radical that now exhibits high regioselectivity (97.5:2.5) for 6-endo closure: an illustration of the synthetic value of this observation is the independent synthesis of the model cyclohexyl sulfone 61 in high yield. It is found that ring closure under the conditions employed occurs irreversibly in all cases.
- Della, Ernest W.,Graney, Sean D.
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p. 3824 - 3835
(2007/10/03)
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