36847-51-5Relevant articles and documents
Base-promoted diastereoselective α-alkylation of borane: N -((S)-1′-phenylethyl)azetidine-2-carboxylic acid ester complexes
Tayama, Eiji,Nishio, Ryotaro,Kobayashi, Yoshiaki
supporting information, p. 5833 - 5845 (2018/08/22)
The base-promoted α-alkylation of N-((S)-1-phenylethyl)azetidine-2-carboxylic acid esters 1 was investigated. The use of diastereomerically pure borane complexes 3 as substrates, which are easily prepared from 1, dramatically improved the yields and diastereoselectivities of α-alkylated products 2. For example, the treatment of tert-butyl ester (1S,2S,1′S)-3a with 2.4 equivalents of lithium bis(trimethysilyl)amide (LiHMDS) at 0 °C followed by 2.6 equivalents of benzyl bromide afforded α-benzylated (2S,1′S)-2aa in 90% yield as almost a single diastereomer. Our method enables the production of optically active α-substituted azetidine-2-carboxylic acid esters starting from commercially available (S)-1-phenylethylamine, which is one of the least expensive chiral compounds.
Synthesis of the cytotrienin A core via metal catalyzed C-C coupling
Roessle, Michael,Del Valle, David J.,Krische, Michael J.
supporting information; experimental part, p. 1482 - 1485 (2011/05/15)
A synthetic approach to the C17-benzene ansamycins via metal catalyzed C-C coupling is described. Key bond formations include direct iridium catalyzed carbonyl crotylation from the alcohol oxidation level followed by chelation-controlled Sakurai-Seyferth dienylation to form the stereotriad, which is attached to the arene via Suzuki cross-coupling. The diene-containing carboxylic acid is prepared using rhodium catalyzed acetylene-aldehyde reductive C-C coupling mediated by gaseous hydrogen. Finally, ring-closing metathesis delivers the cytotrienin core.
Preparation of β-lactams from azetidine-2-carboxylic acids and esters
Wasserman,Lipshutz,Tremper,Wu
, p. 2991 - 2999 (2007/10/02)
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