A Practical and Stereoconservative Synthesis of (R)‐3‐Amino‐4‐(trimethylammonio)butanoate [(R)‐Aminocarnitine], and Its Trimethylphosphonium and Simple Ammonium Analogues Starting from D‐Aspartic Acid

Abstract

We have developed a new stereospecific synthesis of (R)‐aminocarnitine using D‐aspartic acid as the starting material. This strategy, which is simple and amenable to an industrial scale‐up, gives the target compound in six steps and in fairly good overall yields (41%). Other aminocarnitine related molecules such as optically pure (R)‐3‐amino‐4‐(trimethylphosphonio)butanoic acid and (R)‐3,4‐diaminobutanoic acid dihydrochloride have also been prepared according to the same synthetic strategy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Organocatalytic Preparation of Simple β-Hydroxy and β-Amino Esters: Low Catalyst Loadings and Gram-Scale Synthesis

“…Finally, it was shown that the obtained β-amino esters can be easily converted to the parent amino acid by saponification by using K 2 CO 3 in a H 2 O/MeOH mixture, as demonstrated for the synthesis of amino acid 6 (Scheme ). Tosyl deprotection without racemization can be realized by using aq HBr, PhOH, and heating, as reported for 6 …”

Photoredox-Mediated Remote C(sp3)–H Heteroarylation of N-Alkyl Sulfonamides

“…As shown in Scheme , the reaction of 4-chloroqunoline 2 with 4- tert -butylphenylsulfonyl pentylamine 1 conducted at 1 mmol scale worked well, giving product 3 in 74% yield. The 4- tert -phenylsulfonamide group in product 5 can be cleanly removed by the treatment of phenol in the aqueous hydrobromic acid at 130 °C to give free amine product 20 in 90% yield …”

“…The combined organic phase was dried over Na 2 SO 4 , filtered, and concentrated in vacuo. The crude product was purified by flash chromatography on silica gel (DCM/MeOH = 5:1) to give compounds 20 in 90% yield (41 mg) as yellow oil …”

Constrained Cyclic β,γ‐Diamino Acids from Glutamic Acid: Synthesis of Both Diastereomers and Unexpected Kinetic Resolution

“…For example, the natural α-amino acid L-proline is known to form polyproline helices, [1] or to generate turns when associated with glycine. [20][21][22][23][24][25] This pattern is present in some biologically active compounds such as pseudotheonamide A 1 , [26] aminocarnitine, [27] and deoxyaminostatine, [28] but the main interest in this motif lies in its use as either a -amino acid or a γ-amino acid building block for foldamers. [2][3][4][5][6][7][8][9] A large variety of helices, [10][11][12][13][14] turns, [15] sheets, [16] and ribbons [17,18] have been observed in this way, even in the less explored area of γ-peptides.…”