Asymmetric Synthesis of Naturally Occuring Spiroketals

Asymmetric synthesis of naturally occurring spiroketals.

Spiroketals are widely found as substructures of many naturally occurring compounds from diverse sources including plants, animals as well as microbes. Naturally occurring spiroketals are biologically active and most of them are chiral molecules. This article aims at reviewing the asymmetric synthesis of biologically active spiroketals for last 10 years (1998-2007).

Prolycopene, a Naturally Occuring Stereoisomer of Lycopene.

-Spores of the fungi Rhizopus suinus, Mucor dispersus and Aspergillus melleus were tested with respect to their resistance to ultraviolet of wave-length 2650 A. Sigmoid survival curves were obtained for the fungi Rhizopus suinus and the minus strain of Mucor dispersus when spores from 4-day cultures were irradiated. Survival curves describing a logarithmic order of death were exhibited by spore...

A Naturally Occuring Teratology in the Red Imported Fire Ant

Ultrastructural study of naturally occuring ovine pulmonary adenocarcinoma in Fars province, Iran

Ovine pulmonary adenocarcinoma (OPA) was studied in the lungs of 15 naturally-affected sheep (9 with classical and 6 atypical lesions) by transmission electron microscopy. Two lung samples from normal sheep were used to develop the ultrastructural criteria. Pathologic lesions consisted of focal-multifocal to coalescent nodules or masses in the cranioventral or diaphragmatic lobes. Ultrastructur...

Nitroalkanes as central reagents in the synthesis of spiroketals.

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...