Menthone derived ligands

Treatment of the (—)-menthone-derived 2/7-1,3-benzoxazin-4(3//)-one 202 with triflic anhydride gave the triflate 203 in quantitative yield. Palladium-catalyzed cross-coupling of 203 with 2-pyridylzinc halide resulted in formation of an approximately 3 1 mixture of the 4-(2-pyridyl)-2//-l,3-benzoxazine 204 and a 4-imino-l,3-benzodioxane derivative 205 (Scheme 36). Compound 205 was formed by the isomerization of 203, which occurred with complete retention of stereochemistry. The 4-(2-pyridyl)-l,3-benzoxazine derivative 204 was applied in enantioselective allylic alkylations of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate as a chiral ligand inducing a 62% ee in the product <2005JOM(690)2027>. 

Faraone and coworkers studied the hydroformylation of methyl acrylate by using a cationic rhodium complex bearing a / Af-ligand derived from (—)-menthone (Scheme 4.82) [57]. The branched aldehyde was preferentially formed with 92% ee. 

Godau T, BleifitB SM, MitUer AL, et al. Cu(I) catalysed cyclopropanation with enantiopure scorpionate type ligands derived from (+)-camphor or (—)menthone. Dalton Trans. 2011 40 6547-6554. 

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