Pregnane skeleton

Scheme 19.2 N umbering and ring letters of the pregnane skeleton.

The steroid molecule provides, for example in the pregnane skeleton (x), twenty-one carbon atoms each unique in its steric environment. With simple functional groups (hydroxyl, carbonyl, olefinic, etc.) available at virtually every one of... 

Potassium cyanide, 129 Pre-calciferol, 414, 417-418 Prednisone acetate, 191 —, photolysis, 425, 428-429 Pregnane side chain, conformations, 12, 139 —degradation, 344, 346 Pregnane skeleton, 2. 3 Product development control , X36, 139... 

The presence of two hydroxyls (one of them allylic), one dimethyl-amino group, and two secondary tertiary double bonds in the pregnane skeleton of this alkaloid was established from IR- and XMR-spectra. Comparison of the NMR-spectrum with those of the stereoisomeric 3,16-dihydroxypregna-5,17(20)-dienes reported in the literature 60) showed that the signal of the 18-methyl occupied the position (9.24 t) which was in agreement with the a orientation of the 16 hydroxyl and trans configuration of the olefinic side chain as expressed in the formula LXVIII 59). 

The absence of a double bond in the pregnane skeleton shows that spiropachysine should be hexacyclic. Since the amido-group has been shown to be at C-3,... 

A review of the Buxus alkaloids with the 9/3,19-cyclo-14a-methyl-5a-pregnane skeleton has been published/ Pseudocyclobuxine D (67), the 3-epimer of cyclobuxine D, was isolated from Buxus sempervirens Structural assignment was achieved by i.r., n.m.r., and m.s. studies. Buxtauine, cyclomicrobuxine, cyclobuxine D, cycloprotobuxine C, and Na-benzoylcycloxobuxidine F have been isolated from the leaves of Buxus hyrcana Pojark. ... 

Pachysandra termimlis (Buxaceae) is a perennial plant that grows in the shade in various locations in Japan and other temperate zones. This plant contains about 0.7% alkaloids in the dried above-ground parts the main alkaloids are pachysandrine A and pachystermine A [2]. These compounds possess the pregnane skeleton, which has a C2 imit remaining at the C-17 position, with two nitrogen atoms incorporated at the C2 side-chain and at C-3. 

Cyproterona aeatata, I7a-acetoxy 6-chloro-la,2a-methylenepregna-4,6-diene-3,20-dioue an antiandrogen steroid containing a pregnane skeleton. It counteracts the effects of the male sex hormone, tes-... 

Both South American and African species of Malouetia A. DC., also Apocynaceae and the genus to which guachamacd belongs (Section 1.2.1.2), have been investigated chemically and found to contain a range of steroidal alkaloids based on the pregnane skeleton (for a review, see 77). The bis-quaternary base malouetine (53), extracted from bark of the African M. bequaertiana Woodson, is undoubtedly the most interesting of these (76, and references cited therein). South American species have been less well studied and only in M. arborea (Veil.) Miers have traces of quaternary bases been detected. See further Section 1.6.4.1. 

The 4,4,14-trimethyl-9(10->19)aZ)c<9-pregnane skeleton is the basic structure of a small group e.g., N-isobutyryl buxidienine-F and N-iso-butyryl buxaline F, 331 and 332, respectively) within the Buxus alkaloid family. The majority of the Buxus alkaloids appear to be degraded... 

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