Synthese von enantiomerenreinen ‘Grasshopper’‐Ketonen und verwandten Verbindungen

Abstract

Synthesis of Optically Pure Grasshopper Ketone and of Its Diastereoisomers and Related CompoundsStarting from our previously described synthon 1, the synthesis of four enantiomerically pure grasshopper ketons (diastereoisomeric 4-(2', 4'-dihydroxy-2', 6,6-trimethylcyclohexylidene)but-3-en-2-ons) and of their 0x0 derivatives was performed. Spectral and chiroptical data are presented.

Highly Efficient Stereocontrolled Total Synthesis of the Polyfunctional Carotenoid Peridinin

“…This is the first example in which the stereochemistry between the C3 hydroxy group and the C5, C6 epoxide in the cyclohexane terminal of carotenoids was satisfactorily controlled. [4,8] The stereocontrolled synthesis of the allene segment 2 from 4 is shown in Scheme 3. The preparation of the allylic…”

Allenyl and Alkynyl Phenyl Ethers from the Endolichenic Fungus Neurospora terricola

“…8 Alkynes are important bioactive natural products showing cytotoxic, anti-inflammatory, and antiprotozoal effects [16][17][18] and are commonly used as the building blocks in synthesis of allenyl natural products. [19][20][21][22] Compounds 1-6 are the first secondary metabolites to be reported from the endolichenic fungus Neurospora sp. and the third examples of natural products discovered from endolichenic fungal sources.…”

Confirmation of the Structures of Lutein and Zeaxanthin

“…These deviations from planarity are caused by small twists about the bonds, with the maximum twist about any one bond being 13.3(4)8 in 1i and 7.8(5)8 in 2b. Interestingly, this maximum twist occurs about the same bond, C(28)ÀC (29), in both compounds. Contrary to the usual observations, some of the largest twists occur about the CC bonds.…”

“…See [29]. Signals in the 13 C-NMR spectra are not completely assigned, and some of the assignments especially in the olefinic region may need interchange (*).…”