Intramolecular Diels−Alder Cycloadditions of Fulvenes. Application to the Kigelinol, Neoamphilectane, and Kempane Skeletons

Abstract

A variety of polycyclic ring skeletons (e.g., kigelinol, neoamphilectane, and kempene systems) can be prepared rapidly via intramolecular Diels-Alder cycloadditions (IMDA) of fulvenes. The length of the tethers and the diversity of the substituents on the fulvene core dictate the nature of the IMDA pathway. [reaction: see text]

Highly Controlled Gas/Liquid Processes in a Continuous Lab‐Scale Device

“…2. FutureChemistry's FlowStart Evo [27] was used to pump the solution(s) into the microreactor, in which the solvent/CO 2 mixture and the substrate (1, B) were reacted to produce the carboxylate salt (2). 3) [26].…”

“…At the laboratory scale on the other hand, the use of reactive gases is less obvious and is mainly focused on hydrogenation and ozonolysis [1,2]. At the laboratory scale on the other hand, the use of reactive gases is less obvious and is mainly focused on hydrogenation and ozonolysis [1,2].…”

Structures of 6-(substituted-phenyl)fulvenes

“…From their quite reactive, electron-poor double-bond between C1 and C6, fused ring systems can be built up [1]. On the other hand, the rather electron-rich double-bonds in the five-membered ring readily undergo Diels-Alder-reactions with various electron-poor dienes to yield fused-ring-compounds [2,3]. For synthetic inorganic chemistry purposes, fulvenes have proven to be very useful starting materials for the synthesis of metallocenes bearing one ring substituent [4].…”

“…m.p. 96 C. Crystals were grown from petroleum spirit (40-60 C) C 9 H 6 ); 55.6 (OCH3 ). IR absorption (cm À1 KBr): 3052 (w); 2938 (w); 2848 (w); 1593 (C¼C m); 1502 (m); 1250 (m); 1175 (m); 1026 (m); 824 (m); 748 (s); 684 (s); 500 (m).…”

Stereoselective and Modular Assembly Method for Heterocycle‐Fused Daucane Sesquiterpenoids

“…After successfully assembling the nordaucane scaffolds 6-15 with ten different fused heterocyclic moieties, belongingt o eight different classes, we next turnedt ot he elaboration of a complete daucane sesquiterpene framework (Scheme 2), which requires an extra carbon att he terminal position of the 1,3diene.F or this, satisfactory results were obtained using ac hemoselective vinylogous Horner-Wadsworth-Emmons reaction on keto-aldehyde 1. [20] The resulting keto-ester 16 could in turn undergo ac hemoselective furyllithium addition, but the resultingf urfuryl alcohol 17 failed to give any annulated products, mainly returning simple dehydration (triene)p roducts. An additional reduction step then afforded the cycloaddition precursor 18,f eaturing am ore nucleophilic diene moiety,w hich smoothly underwent cycloaddition to the functionalized furanodaucane 19,w ith complete stereoselectivity for the formation of three new stereocenters.…”