Configurational and conformational analyses of α-methylene-γ-butyro steroidal spirolactones

Combining Ring-Closing Metathesis and Hydroformylation Strategies: A Novel Approach to Spirocyclic γ-Butyrolactones

“…Spirocyclic γ-butyrolactones not only are widespread in nature − but have also played a key role as synthetic intermediates. − One example of a natural product with a spirocyclic γ-butyrolactone moiety is the alkaloid stemotinine, and the antitumor antibiotic aranorosin may serve as an example where a spirocyclic lactone has been used as a key intermediate in the total synthesis (Chart ). Furthermore, a variety of methods are available for the conversion of γ-butyrolactones into α-methylene-γ-butyrolactones .…”

“…Furthermore, a variety of methods are available for the conversion of γ-butyrolactones into α-methylene-γ-butyrolactones . Spirocyclic, steroidal derivatives of these compounds often show outstanding biological properties. , In principle, one can imagine two different strategies for the construction of spiro compounds: (i) the conversion of a tetrafunctional acyclic compound into a spirocyclic system in a one-pot reaction or (ii) the stepwise formation of two carba- or heterocycles via a monocyclic intermediate. A variety of methods for the synthesis of lactones is available, for example, lactonization after asymmetric dihydroxylation, iodolactonization, palladium-catalyzed cyclization of allenic or homopropargylic carboxylic acids, or samarium-mediated addition of ketones to acrylates.…”

A Short and Efficient Synthesis of 3-Spiro-α-methylene-γ-butyrolactone Oxindolones from Isomerised Bromo Derivatives of Morita-Baylis-Hillman Adducts

“…9 Consequently, there has been considerable interest in developing efficient methods for the synthesis of spirolactones. [10][11][12][13][14][15][16][17] Morita-Baylis-Hillman (MBH) adducts and their derivatives such as halides, acetates, and ethers play an important role as synthons for the synthesis of a wide spectrum of natural products. 18 Metal-mediated reactions are well known in the myriad of C-C bond-forming reactions.…”