104883-53-6

Upstream product

• 109-52-4 valeric acid 
• 838839-44-4 4-butylidene-2,2,6,6-tetramethyl-3,5-dioxa-2,6-disilaheptane 
• 537041-94-4 (2S)-N,N-bis[(1R)-1-phenylethyl]-3-{[(1S)-1-phenylethyl]amino}-2-propylpropanamide 
• 537041-99-9 (S)-2-Aminomethyl-pentanoic acid bis-((R)-1-phenyl-ethyl)-amide 
• 107-08-4 1-iodo-propane 
• 312613-77-7 (1R,2R)-(+)-pseudoephedrine-β-alanine amide 

Relevant academic research and scientific papers

Catalytic Asymmetric Synthesis of Unprotected β2-Amino Acids

We report here a scalable, catalytic one-pot approach to enantiopure and unmodified β2-amino acids. A newly developed confined imidodiphosphorimidate (IDPi) catalyzes a broadly applicable reaction of diverse bis-silyl ketene acetals with a silylated aminomethyl ether, followed by hydrolytic workup, to give free β2-amino acids in high yields, purity, and enantioselectivity. Importantly, both aromatic and aliphatic β2-amino acids can be obtained using this method. Mechanistic studies are consistent with the aminomethylation to proceed via silylium-based asymmetric counteranion-directed catalysis (Si-ACDC) and a transition state to explain the enantioselectivity is suggested on the basis of density functional theory calculation.

Enantioselective synthesis of β-amino acids Part 13. Diastereoselective alkylation of dianions derived from chiral analogs of β-aminopropanoic acid containing the α-phenylethyl group

Inexpensive acryloyl chloride was converted in 91% overall yield to two derivatives of β-alanine, (R,R,R)-and (R,R,S)-6, containing two chiral auxiliaries. C-Alkylation of (R,R,R)- and (R,R,S)-6 via a dianion derivative, was performed by direct metallation with 2.2 equiv. of lithium hexamethyldisilazane (LHMDS) in THF at - 78°. C-Alkylation of (R,R,S)-6-Li2 ('matched' pair of chiral auxiliaries) afforded the mono-alkylated products 8-11 in 29-96% yield and 54-95% stereoselectivity. Employment of LiCl as an additive generally increased stereoselectivities, whereas the effect of HMPA as a cosolvent was erratic. Chemical correlation of the major diastereoisomer from the alkylation reactions with (S)-α-alkyl-β-alanine (12-15) showed that addition of the electrophile preferentially takes place on the enolate's Si-face. This conclusion is also supported by molecular-modeling studies (ab initio HF/3-21G), which indicate that the lowest-energy conformation for (R,R,S)-6-Li2 presents the more sterically hindered Re-face of the enolate. The theoretical studies also predict a determining role for N-Li-O chelation in (R,R,S)-6-Li2, giving rise to an interesting 'ion-triplet' configuration for the dilithium dianion.

Synthesis of alpha-substituted beta-amino acids using pseudoephedrine as a chiral auxiliary.

[reaction: see text] beta-Amino acids are becoming increasingly attractive as intermediates in the synthesis of a variety of molecular structures. However, few methods are available for the synthesis of alpha-substituted beta-amino acids that are both readily scalable and highly stereoselective. Herein we report a new method for synthesizing alpha-substituted beta-amino acids that satisfies both of these requirements using enantiomerically pure pseudoephedrine as a chiral auxiliary.