Antibiotics terpenoid

In essence, an enzyme-catalyzed equivalent exists for almost every type of chemically catalyzed reaction, and thousands of these have been documented in comprehensive monographs and reviews (9-26). Many reactions have been observed in relatively specialized areas, particularly with groups of organic compounds such as the steroids, other terpenoids, antibiotics, aromatics, and alkaloids. Specific chemical reactions have been accomplished with intact and growing microbial cells, with plant and mammalian tissue preparations, and with... 

Synthesis of the terpenoid antibiotic LL-Z1271a. Adinolfi, M. Mangoni, L. Barone, G. Laonigro, G. Gazz. Chim. Ital. 1973,103,1271-1279. 

Tel. 44-071-865-0066, fax 44-071-522-9621 Database of more than 80,000 alkaloids, terpenoids, antibiotics, peptides, carbohydrates, lipids, steroids, flavinoids, and related compounds. Dictionary of Organic Compounds. Dictionary of Analytical Reagents. On CD-ROM for PCs. 

A full paper on the biogenetically patterned syntheses of the levantenolides outlined earlier has appeared. A simple route to 4,4-disubstituted c/s-decalins has been reported involving the use of the dimethanesulphonate (123) to alkylate diethyl malonate. In the product (124) the ester groups may be selectively hydrolysed. A full paper describing the synthesis of marrubiin has appeared and the approach has been extendedto the synthesis of the terpenoid antibiotic LL-Z 1271. The lactone (125) was converted into the ester (126), which was oxidized with selenium dioxide to form the lactol (127). 

Fifteen terpenoid antibiotics are included in this chapter two additional ones are discussed elsewhere in this book (mycelianamide and fumagiUin). All these substances contain carbon, hydrogen, and at least two oxygens. All are either monoterpenoids (comprised of two Cg units), sesquiterpenoids (three Cg units), or triterpenoids (six Cg units). Since most of the terpenoids are of these three types, this is hardly surprising a few diterpenoid (four Cg units) and carotenoid (eight Cg units) antibiotics will probably eventually be found. In some of the terpenoid antibiotics (e.g. grifohn and eburicoic acid), carbon atoms not derived from isopentenyl pyrophosphate (I) have become attached to terpenoid units in others (e.g. helvoHc acid and pristimerin), carbon atoms have been lost at some stage in the biosynthesis. 

The biosynthesis of several terpenoids, including some of the terpenoid antibiotics, have been studied at the second level, generally with the aid of or tritium. There has been speculation regarding the biogenetic pathway to almost every terpenoid. The pioneer in this area has been Ru iCka, many of whose farsighted predictions (Ru iCka et al., 1953) have been verified. Thus, the study of the biosynthesis of terpenoids and terpenoid antibiotics is in its infancy. Many of the bare outhnes of the pathways are known, but much work is needed to complete the pictures. 

Of the terpenoid antibiotics so far discovered, grifolin (I) presents the fewest biosynthetic problems. The last step in its biogenesis apparently consists of the alkylation of orcinol (II), a well-known lichen constituent, with trans-trans-farnesyl pyrophosphate. Orcinol (II) is one of the simplest acetate condensation products, and is derived as shown by decarboxylation of orseUinic acid (III), a fungus and lichen constituent whose biogenesis from acetate has been exten-... 

---