Author : Daniel Chorley
Publisher :
ISBN 13 :
Total Pages : 361 pages
Book Rating : 4.:/5 (935 download)
Book Synopsis Synthetic Studies Towards 5,5-Benzannulated Spiroketals Isolated from Traditional Chinese Medicines by : Daniel Chorley
Download or read book Synthetic Studies Towards 5,5-Benzannulated Spiroketals Isolated from Traditional Chinese Medicines written by Daniel Chorley and published by . This book was released on 2015 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes synthetic endeavours towards two families of 5,5-benzannulated spiroketals isolated from plants used in traditional Chinese medicine: the danshenspiroketallactones and the pinnatifinosides. The first part of this thesis describes the successful synthesis of danshenspiroketallactone (14) and epi-danshenspiroketallactone (15). Danshenspiroketallactone (14) was isolated in 1985 by Rao et al. from Chinese Sage (Salvia miltiorrhiza), a plant used in traditional Chinese medicine to treat cardiovascular disease. In 1988 epi-danshenspiroketallactone (15) was isolated from S. miltiorrhiza by Snyder et al. These natural products possess a 5,5-spiroketallactone moiety fused to a naphthalene ring and are epimeric at the spiroketal centre. Key features of the total synthesis described herein are a directed ortho-metalation/lactonisation procedure used to unite the aromatic and aliphatic fragments of the molecule and form the lactone ring, and an oxidative radical cyclisation by intramolecular hydrogen abstraction used to complete the spiroketal. The second part of this thesis presents synthetic attempts towards pinnatifinosides C (18) and D (19), two members of the pinnatifinosides family of 5,5-spiroketal flavone containing natural products isolated by Zhang et al. in 2001 from Chinese Hawthorn (Crataegus pinnatifida). Two benzannulated spiroketal model compounds possessing the core of the pinnatifinosides were synthesised using a key Sonogashira cross-coupling reaction and gold-catalysed spiroketalisation. While the final spiroketalisation step of the attempted total synthesis of pinnatifinosides C (18) and D (19) using methods developed during the initial model studies proved unsuccessful, these investigations have established a sound platform that will enable further synthetic efforts towards pinnatifinosides C (18) and D (19), and other related compounds.