61996-79-0Relevant articles and documents
Synthesis of Pyranocyclopentaindolines Representing the Western Sections of Janthitrem B, JBIR-137, and Shearinine G
Fresia, Marvin,Lindel, Thomas
supporting information, (2022/02/05)
The synthesis of the ABCD tetracyclic partial structures of the fungal indole diterpenes janthitrem B, JBIR-137, and shearinine G is reported. The route starts from 5-formylated indoline that is coupled to a dihydropyran moiety, followed by Prins cyclization. A diene was obtained that was oxygenated in a divergent manner. The hydroxylated tetracyclic western half of janthitrem B was obtained in eight steps and 10 % overall yield. We also share our experience with alternative approaches passing via alkynylated precursors. This includes the gold-catalyzed cycloisomerization of a 6-ethynyl-5-prenylindoline.
Unsaturated aldehydes as potential lilial replacers
Schroeder, Martin,Mathys, Marion,Ehrensperger, Nadja,Büchel, Michelle
, p. 1651 - 1673 (2015/02/19)
A series of Claisen rearrangements was undertaken in order to find a replacement for Lilial (= 3-(4-(tert-butyl)phenyl)-2-methylpropanal), a high-tonnage perfumery ingredient with a lily-of-the-valley odour, which is a CMR2 material [1]. 5,7,7-Trimethyl-4-methyleneoctanal (10), the synthesis of which is described, became the main lead. It possesses an odour which is very close to that of Lilial but lacks its substantivity. Aldehydes with higher molecular weights than that of 10 were, therefore, synthesised in order to boost substantivity and to understand the structural requirements for a 'Lilial' odour. The aldehydes were obtained via Claisen rearrangements of 'exo-methylidene' vinyl ethers, allenyl vinyl ethers, or allenyl allyl ethers. Alternatively, coupling of terminal alkynes with allyl alcohols led to the desired aldehydes. Derivatives of 10 and their sila analogues were also synthesised. The olfactory properties of all synthesised molecules were evaluated for possible structure-odour relationships (SOR).
Enantioselective copper-catalysed propargylic substitution: Synthetic scope study and application in formal total syntheses of (+)-anisomycin and (-)-cytoxazone
Detz, Remko J.,Abiri, Zohar,Le Griel, Remi,Hiemstra, Henk,Van Maarseveen, Jan H.
experimental part, p. 5921 - 5930 (2011/06/26)
A copper catalyst with a chiral pyridine-2,6-bisoxazoline (pybox) ligand was used to convert a variety of propargylic esters with different side chains (R=Ar, Bn, alkyl) into their amine counterparts in very high yields and with good enantioselectivities (up to 90% enantiomeric excess (ee)). Different amine nucleophiles were applied in the reactions and the highest enantioselectivities were obtained for aniline and its analogues. Interestingly, some carbon nucleophiles could also be used and with indoles excellent ee values were obtained (up to 98% ee). The versatility of the propargylic amines obtained was demonstrated by their further elaboration to formal total syntheses of the antibiotic (+)-anisomycin and the cytokine modulator (-)-cytoxazone. Copyright
