Sulforaphane, synthesis

Biocatalytic access to both antipodal sulfoxides was exploited in total syntheses of bioactive compounds, which is outlined in some representative examples. Biooxidation of functionalized dialkyl sulfides was utilized in the direct synthesis of both enantiomers of sulforaphane and some analogs in low to good yields and stereoselectivities (Scheme 9.27) [206]. This natural product originates from broccoli and represents a potent inducer of detoxification enzymes in mammalian metabolism it might be related to anticarcinogenic properties of plants from the cruciform family. All four possible stereoisomers of methionine (R = Me) and ethionine sulfoxides... 

The usefulness of the approach in producing methanesulfinates in high de was demonstrated by the synthesis of both isomers of sulforaphane 68, a naturally occurring sulfoxide that has been shown to stimulate the production of carcinogen-detoxifying enzymes97 (Scheme 20). 

Sulforaphane nitrile (R(CN)-N=C = S) Pro-inflammatory protein synthesis blockage (For many inhibitors of NFKB-mediated iNOS COX expression see Tables 7.3 8.1) From Glucoraphanin Induces GST, NADPH quinone reductase [indirect AO] 14.4B... 

Posner GH, Cho C-G, Green JV, Zhang Y, Talalay P. Design and synthesis of bifunctional isothiocyanate analogs of sulforaphane correlation between structure and potency as inducers of anticarcinogenic detoxification enzymes. J Med Chem i994 37 i70-i76. 

Baker s yeast (Saccharomyces cerevisiae) contEiins a desaturase which is able to oxidize some almost symmetrical sulfides such as methyl thiostearate [132]. A less symmetrical sulfide. Bn—S—(CH2)t—C02Me, has been oxidized by Saccharomyces cerevisiae into an (S)-sulfoxide with 70% ee. The stereochemical course of the oxidation by 5. cerevisiae of quasisymmetrical sulfides such as methyl 9-thiastearate has been established and found highly enantioselective (>95% ee) [133]. Recently, biosulfoxidation by the fungus Helminthosporium ARRL 4671 has been applied to the synthesis of (R)-(-)-sulforaphane (54a) (Scheme 1.13) [134]. This compound has interesting biological properties. 

Ru(SR R )Gp (highly stereoselective (de = 46-98%). Such oxidation reactions have been applied to the preparation of the natural product sulforaphane 169 starting from phthalimidobutyl methyl sulfide 168 and the chloride complexes [RuGlGp(P-P)] (P-P = dppe, (S,S)- or (i ,i )-chiraphos) (Scheme 7). The use of those precursors containing the optically pure chiraphos ligands allowed the enantioselective synthesis of the R- and S- enantiomers of sulforaphane (80% ee). 

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