Iron-Catalyzed Grignard Cross-Couplings with Allylic Methyl Ethers or Allylic Trimethylsilyl Ethers

Abstract

We have found that cross-coupling between aryl Grignard reagents and allylic methyl ethers proceeded well in the presence of a catalytic amounts of Fe(acac)3 to afford the corresponding allylic substitution products in good yields. Under the same conditions, allylic trimethylsilyl ethers also reacted with Grignard reagents to give the corresponding cross-coupling products.

Asymmetric Synthesis of Trisubstituted Vicinal Diols through Copper(I)‐Catalyzed Diastereoselective and Enantioselective Allylation of Ketones with Siloxypropadienes

“…Without quenching the reaction occurring in the presence of 5 mol % Cu‐( R , R P )‐TANIAPHOS complex with TBAF, TBS ‐ syn ‐ 3 a was obtained in 97 % yield with >20/1 dr and 99 % ee. Interestingly, this chiral silyl‐ether served as a wonderful substrate in the Fe‐catalyzed arylation, [25] which was transformed to allyl alcohol 4 in 98 % yield with >20/1 E / Z and 99 % ee. Remarkably, the present syn ‐selective reaction worked efficiently in the presence of only 0.1 mol % Cu‐( R , R P )‐TANIAPHOS complex ( syn ‐ 3 a , 83 %, 13.7/1 dr, 99 % ee).…”

Visible-light-mediated decarboxylative (E)-alkenylation of aliphatic carboxylic acids with aryl styryl sulfones under metal-free conditions

“…Secondly, we capitalized on the fact that 2-phenoxycarboxylic acids are suitable substrates for this method by performing an iron-catalyzed allylic substitution of the phenoxy group in 3aa by a phenyl ring, 31 using an excess of phenylmagnesium bromide to obtain ( E )- 7 as a single isomer. 32 This transformation allows the preparation of ( E )-alkenes that are not accessible using our decarboxylative alkenylation approach since aromatic or primary carboxylic acids are unsuitable substrates. Moreover, the samarium catalyzed intramolecular iodoarylation of 3ab was accomplished with N -iodosuccinimide (NIS), obtaining the corresponding chromane 8b in an excellent yield and with trans -configuration.…”

Transition-Metal-Catalyzed Cross-Coupling Reactions of Grignard Reagents

“…Nagano and co-workers (2018) reported the Fe(acac) 3 cross-coupling between aryl Grignard reagents and allylic methyl ethers to afford allylic substitution products in good yields; allylic trimethylsilyl ethers also reacted with Grignard reagents to give the corresponding cross-coupling products. 121 Li and co-workers reported the Fe(acac) 3 -catalyzed, selective allylic C-O bond cleavage using ethyl salicylate as a directing leaving group in coupling with aryl and alkyl Grignard reagents to give allyl-substituted arenes and alkanes (Scheme 53). 122 Excellent selectivity of C-O bond cleavage was achieved in multiple allylic C-O bond containing substrates with the aid of this salicylate-directed strategy.…”