Chemistry of L-Ascorbic Acid: Regioselective and Stereocontrolled 2-C- and 3-C-Allylation via Thermal Claisen Rearrangement

Mixtures of Ascorbyl-stearate and Vitamin D3: A Monolayer Study at the Gas/Water Interface

“…If the two components show an ideal miscibility, g 1 Å g 2 Å 1, and the experimental values of p c,m should be identical to the theoretical predictions. On the experimental and theoretical values is directly related to the De Å RTj 6 [8] interactions between the two components. In the ideal case, and when p c,1 É p c,2 , the exponentials that appear in Eq.…”

L-Ascorbic Acid: Properties and Ways of Modification (A Review)

“…3-O-alkyl derivatives 22 were obtained selectively (albeit with relatively low yields not exceeding 50%) via the interaction of compound 5a in DMSO with excess alkyl halides containing saturated alkyl groups in the presence of NaHCO 3 [19]. Reactions between K 2 CO 3 and equimolar amounts of alkyl halides in DMSO yield a mixture of 3-O-alkylated products 22 and 2,3-di-Odialkylated products 23 [20]. In anhydrous acetone, 3-O-alkylated derivatives 22 were the only reaction products (scheme 8) [21].…”

“…The only commonly accepted conclusion based on the obtained data was that an increase in the yield of 2-C-alkylated product is favored by prolonged incubation and high reaction temperature. In particular, a 6-h boiling of 5,6-O-isopropylidene-3-O-allyl-L-ascorbic acid 64a in toluene leads to a 100% rearrangement of the allyl group into the 2-C position with the formation of a mixture of diastereomeric 2-C-alkylated products 65a and 66a (scheme 24) [20]. Thus, it was established that the kinetically preferred 3-O-alkylated products can rearrange into thermodynamically more stable 2-C-alkylated products.…”

Transannular Rearrangement of Activated Lactams: Stereoselective Synthesis of Substituted Pyrrolidine‐2,4‐diones from Diketopiperazines

“…[1] This serendipitous C aminoacylation of amino acids could allow the straightforward synthesis of highly valuable pharmacological scaffolds. Analogous structures to those of the pyrrolidine-2,4-dione derivatives are present in various natural and synthetic compounds, such as ascorbic acid, [2,3] which displays a broad range of well-known biological properties, and tetramic acid, [4] which exhibits antibacterial and antiviral activities. Furthermore, pyrrolidine-2,4-diones serve as significant intermediates in the synthesis of statins, [5][6][7][8][9][10][11] a key structural motif found in peptidomimetic inhibitors of proteases, such as aspartic proteases.…”

“…To expand the scope of the TRAL reaction, the asymmetric Claisen-like rearrangement described for 3-O-allyl-(isopropylidene) ascorbate [2] was applied to the pyrrolidine-2,4-dione derivative 2 e, following its conversion into 6 by O allylation, to give compound 7 in a stereoselective manner (Scheme 3). The TRAL/alkylation and Claisen-like rearrangement were both found to be completely diastereoselective reactions.…”