[reaction: see text] The first stereoselective synthesis of (-)-acanthoic acid (1) has been designed and accomplished. Our synthetic plan departs from (-) Wieland-Miesher ketone (7) and calls upon a Diels-Alder cycloaddition reaction for the construction of the C ring of 1. The described synthesis confirms the proposed stereochemistry of 1 and represents an efficient entry into an unexplored cl...

Development of new synthetic reactions that feature a tandem process triggered by Brook rearrangement, a C-to-O 1,2-anionic shift of a silyl group, will be discussed. A basic motif for the strategy is the generation of an alpha-siloxy carbanion by the reaction of acylsilanes with ketone enolates and then trapping the anions by intra- and inter-molecular electrophiles. For example, the reaction ...

For an improved synthesis of the recently described expanded octamethoxycubane with a central C56 core, formally obtained by inserting buta-1,3-diynediyl moieties into all C(sp3)-C(sp3) bonds of octamethoxycubane, the preparation of the optically pure methyl ether of a differentially silyl-protected trispropargylic alcohol was required. The key step of the preparation involved a diastereoselect...

The asymmetric unit of the title compound, C21H16ClNO4, contains two independent mol-ecules (A and B), each adopting a conformation wherein the isoxazole ring is roughly orthogonal to the anthrone ring. The dihedral angle between the mean plane of the isoxazole (all atoms) and the mean plane of the anthrone (all atoms) is 88.48 (3)° in one mol-ecule and 89.92 (4)° in the other. The ester is alm...

In the title compound, C(25)H(16)N(2)O(8), the dihedral angle between the naphthalene ring system and the benzene ring of the nitro-phenyl ketone unit is 82.64 (7)°. The bridging ester O-C(=O)-C plane makes dihedral angles of 42.12 (8) and 11.47 (9)°, respectively, with the naphthalene ring system and the benzene ring of the nitro-phenyl ester unit. In the crystal, two types of weak inter-molec...

An efficient synthesis of the N-methylwelwistatin tetracyclic core in only two steps from Kornfeld's ketone is described, whose key transformation involves the generation of a fused bicyclo[4.3.1]decane ring system through a one-pot sequence comprising a Michael-intramolecular aldolization anionic domino process and a DBU-promoted hydrolysis of the N-pivaloyl protecting group. Besides providing...

The title enamino-ketone, C(11)H(10)Br(2)FNO, has a roughly planar pentenone chain; the maximum displacement of an atom from the pentenone plane is 0.071 (4) Å. The dihedral angle between the benzene ring and the pentenone unit is 77.2 (1)°. Inter-molecular C-H⋯Br and C-H⋯O inter-actions, as well as an intra-molecular N-H⋯O inter-action, are observed. In both methyl groups, each H atom is disor...

Nitroalkanes can be profitably employed as carbanionic precursors for the assembly of dihydroxy ketone frameworks, suitable for the preparation of spiroketals. The carbon-carbon bond formation is carried out exploiting nitroaldol and Michael reactions, while the nitro to carbonyl conversion (Nef reaction) ensures the correct introduction of the keto group. Several spiroketal systems endowed wit...

We report a new efficient gold-catalyzed cyclization of 1,6-diyne-4-en-3-ols to give naphthyl ketone derivatives under ambient conditions. The value of this cyclization is reflected by its applicability to a wide range of alcohol substrates.