Total Synthesis of Sphingofungin F Based on Chiral Tricyclic Iminolactone

Abstract

A new, efficient synthesis of sphingofungin F has been accomplished with 10.4% overall yield in 15 steps. The salient features of the synthesis are the utilization of methyl tricyclic iminolactone 3 for the asymmetric aldol reaction as a key step to introduce two desired stereogenic centers, one-pot reaction for the synthesis of omega-hydroxyketone from epsilon-caprolactone, and an effective one-step deprotection strategy to remove all protecting groups using 0.2 N HCl.

Synthesis of the Revised Structure of Acortatarin A

“…13 C NMR (100 MHz, CDCl 3 ): δ = 135.6 (4 × CH), 132.94 (C), 132.88 (C), 129.90 (CH), 129.89 (CH), 129.6 (CH), 127.8 (3 × CH), 109.2 (C), 79.5 (CH), 77.5 (CH), 64.2 (CH 2 ), 62.6 (CH 2 ), 27.1 (CH 3 ), 27.0 (CH 3 ), 26.8 (3 × CH 3 ), 19.2 (C) ppm. Spectral data were in agreement with literature values 25…”

“…The crude was purified via flash column chromatography (silica gel, ethyl acetate/hexanes, 1:5 as eluent) to give the alcohol (3.60 g, 90 %) as a pale yellow oil. [ α ] D 20 = –0.9 ( c = 2.1, CHCl 3 ), ref 25. [ α ] D 20 = –1.5 ( c = 14.5, CHCl 3 ).…”

DIBAL-Mediated Reductive Transformation of trans-Dimethyl Tartrate Acetonide into ε-Hydroxy α,β-Unsaturated Ester and Its Derivatives

“…This product spectroscopically matched that of the known compound. iv ; [α] D 20 = −1.88 (c 3.41, CHCl 3 ), [lit. iv [α] D 20 = −1.8 ( c 3.4, CHCl 3 )]; 1 H NMR (300 MHz, CDCl 3 ) δ 7.73−7.71 (m, 4 H), 7.43−7.41 (m, 6H), 6.97 (dd, J = 5.7, 15.8 Hz, 1H), 6.14 (d, J = 15.8 Hz, 1H), 4.62 (t, J = 5.7 Hz, 1H), 4.23 (q, J = 7.2 Hz, 2H), 3.88−3.85 (m, 3H), 1.47 (s, 3H), 1.45 (s, 3H), 1.31 (t, J = 7.2 Hz, 3H), 1.10 (s, 9H) ; 13 C NMR (75 MHz, CDCl 3 ) δ 166.0, 144.4, 135.60, 135.57, 132.9, 129.9, 129.8, 127.8, 127.7, 122.1, 109.9, 80.7, 77.5, 63.1, 60.5, 26.9, 26.8, 19.2, 14.2.…”

“…Indeed, many of the literature routes require a long reaction sequence that includes redundant protection-deprotection and/or oxidation-reduction processes and often results in low overall yields ( e.g. 4a : 5 steps from dimethyl L-tartrate, ii 4b : 7 steps from cis-2-butene-1,4-diol, iii 4c : 6 steps from L-tartaric acid, iv 4d : 7 steps from L-tartaric acid, v 4e : 7 steps from L-arabitol, vi etc . vii,viii ).…”

Stereochemistry of the Three-Component Reaction Between the Ley′S Aldehyde, Benzyl Amines, and Trialkyl Phosphites. A New Approach to the Protected Enantiomerically Pure 1-Amino-2,3-Dihydroxypropylphosphonates

“…7 Less known antifungal sphingofungins A-D contain 3,4-diepipolyoxamic acid (2S,3R,4R)-1. 1,2,6 On the other hand, in sphingofungins E and F, [8][9][10] potent immunosuppressants mycestericins A-G [11][12][13][14][15] and myriocin [16][17][18] various α-branched polyhydroxy α-amino acid moieties 2 serve as a polar end of long chain molecules.…”