Asymmetric Synthesis of 2-Substituted Oxetan-3-ones via Metalated SAMP/RAMP Hydrazones
نویسندگان
چکیده
2-Substituted azetidin-3-ones can be prepared in good yields and enantioselectivities (up to 85% ee) by a one-pot procedure involving the metalation of the SAMP/RAMP hydrazones of N-Boc-azetidin-3-one, reaction with a wide range of electrophiles, including alkyl, allyl, and benzyl halides and carbonyl compounds, followed by hydrolysis using oxalic acid.
منابع مشابه
Asymmetric total synthesis of (-)-callystatin A employing the SAMP/RAMP hydrazone alkylation methodology.
[structure: see text] The asymmetric total synthesis of (-)-callystatin A has been achieved. The key steps generating the stereogenic centers rely on the asymmetric alpha-alkylation of aldehydes or ketones exploiting the SAMP/RAMP hydrazone alkylation methodology, as well as an enzymatic enantioselective reduction of a 3,5-dioxocarboxylate. For the construction of the alkene moieties, highly se...
متن کاملThe SAMP-/RAMP -hydrazone methodology in asymmetric synthesis of 4S-ferrugineone and 4S, 5S-ferrugineol: The pheromones of palm weevils
4S-ferrugineone and 4S,5S-ferrugineol as pheromones of palm weevils were synthesized in 3 and 4 steps, respectively, starting from nonane-5-one employing SAMP-/RAMP -hydrazone methodology. 5-nonanone is transformed to its corresponding RAMP hydrazone by reaction with the enantiomerically pure hydrazine RAMP. Metalation with lithium diisopropylamide (LDA) in ether to form azaenolate, followed by...
متن کاملRecent advances in the development of highly enantioselective synthetic methods
Abstract: In the course of the development of modem synthetic methods in the field of asymmetric synthesis the SAMP-/RAMP-hydrazone method opens a highly diastereoand enantioselective route to a great variety of carbonyl compounds, alcohols, amines and heterocycles. In this paper recent advances in the development of biomimetic C-C bond formations, such as the synthesis of C2-symmetric ketodiol...
متن کاملSynthesis of Chiral Fluorinated Hydrazines via Pd-Catalyzed Asymmetric Hydrogenation.
An enantioselective hydrogenation of fluorinated hydrazones has been achieved by employing [Pd(R)-DTBM-SegPhos(OCOCF3)2] as the catalyst, providing a general and convenient method toward chiral fluorinated hydrazines. A broad substrate scope including β-aryl-, γ-aryl-, and alkyl-chain-substituted hydrazones worked efficiently in high yields and up to 94% of enantioselectivity. The reductive ami...
متن کاملSynthesis of highly substituted oxetanes via [2+2] cycloaddition reactions of allenoates catalyzed by a guanidine Lewis base.
The first synthesis of highly substituted 3-alkyl-oxetan-2-ylidenes from allenoates was developed by using the bicyclic guanidine 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as an exceptionally active nitrogen Lewis base catalyst.
متن کامل