New Retinoid Analogs from δ-Pyronene, a Natural Synthon

Abstract

δ‐Pyronene (1), a readily available terpenic synthon, is an excellent raw material for the preparation of numerous terpenic intermediates. Original retinoid analogs such as “iso”‐retinyl acetate (5), “iso”‐retinal (6) and ethyl “iso”‐retinoate (7), in which the cyclogeranyl moiety is functionalized in an unusual position, were prepared from δ‐pyronene.

Clickable Vitamins as a New Tool to Track Vitamin A and Retinoic Acid in Immune Cells

“…1 H NMR (400 MHz, CDCl 3 ) δ 9.49 (s, 1H), 6.39 (d, J = 5.9 Hz, 1H), 5.27 (d, J = 5.9 Hz, 1H), 3.38 (s, 6H), 1.85 (s, 3H); 13 C NMR (101 MHz, CDCl 3 ) δ 194.4, 146.7, 141.5, 99.1, 52.5, 9.5. Spectroscopic data are in agreement with those reported ( 28 ).…”

“…Wittig salt ( 1 in scheme 1 ) was coupled with aldehyde ( 2 in scheme 1 ) to make the protected retinal analogue RE-click in 8% yield. Aldehyde ( 2 in scheme 1 ) was synthesized following a literature procedure, which can be found in scheme 2 ( 28 ). The poor yield is a result of several purification steps, which were required to separate the product from the unreacted aldehyde 2 and the facile deprotection of the acetal group under acidic conditions.…”

Exploring synthetic pathways for nucleosidic derivatives of potent phosphoantigens

“…Thus, we attempted to obtain such derivatives using isoprene as starting material and following previously described procedures. [25][26][27][28][29] In our hands, the 4-hydroxy-2-methylbut-2-en-1-yl acetate (Scheme 1, compound 6) was isolated in poor yields and as an inseparable mixture of E and Z-isomers (ratio 8/2). Therefore, we settled-up a novel synthetic pathway using mesaconic acid as starting material as it enabled us to control the stereochemistry of the double bond (Scheme 1).…”

Synthesis of (−)-α-Kainic Acid via TMSCl-Promoted Pd-Catalyzed Zinc-ene Cyclization of an Allyl Acetate

“…Since allyl acetates are versatile precursors of π-allyl palladium(II) complexes, we replaced the chloride of 9 with an acetoxy group ( 1b , Scheme ), which would be incapable of this unwanted nucleophilic displacement. The synthesis of allylic bromide allylic acetate 12 began with allylic chloride allylic alcohol 10 , readily available in two steps from isoprene . Reaction with KOAc in the presence of a catalytic amount of NaI gave the allylic acetate allylic alcohol 11 in moderate yield (Scheme ).…”

“…To a 0.25 M DMF solution of 10 (2.41 g, 20.0 mmol) were added KOAc (4.12 g, 42.0 mmol), NaI (0.16 g, 1.06 mmol), and H 2 O (5.0 mL). The reaction mixture was stirred overnight and then diluted with water and extracted with EtOAc.…”