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Gold(III) Chloride‐Catalyzed Diastereoselective Alkylation Reactions with Chiral Benzylic Acetates
Author(s) -
Rubenbauer Philipp,
Bach Thorsten
Publication year - 2008
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200700600
Subject(s) - chemistry , nucleophile , electrophile , trimethylsilyl cyanide , stereocenter , carbocation , medicinal chemistry , substituent , alkylation , catalysis , organic chemistry , enantioselective synthesis
Gold(III) chloride was shown to be an efficient catalyst for the diastereoselective CC bond formation of various chiral para ‐methoxybenzylic acetates and different nucleophiles. All electrophilic acetates carried next to the reacting center a stereogenic carbon center bound to a functional group (FG), a methyl substituent and a proton. Selectivities were good ( dr >80/20) in favor of the anti ‐product for FG=COOMe, NO 2 , CN and in favor of the syn ‐product for FG=SO 2 Et, PO(OEt) 2 . The reactions proceed most likely via a free carbocation, in which a face differentation is facilitated by a preferred conformation. Several arene nucleophiles were shown to be compatible with the catalysis conditions providing the corresponding substitution products in high yields (13 examples, 62–98%). Moreover, other nucleophiles (allyltrimethylsilane, trimethylsilyl cyanide, 2,2‐dimethyl‐3‐(trimethylsilyloxy)butane, p ‐toluenesulfonamide, and acetylacetone) reacted with a representative chiral electrophile in a high yielding and diastereoselective fashion.