Results 121 to 130 of about 185,877 (187)

Cembrane- and Casbane-Type Diterpenes from the South China Sea Soft Coral <i>Sinularia nanolobata</i>. [PDF]

Mar Drugs
Dong Y, Xiao X, Yao LG, Liang LF, Li SW, Guo YW.   +5 more
europepmc   +1 more source

Effects of Moisture Content Gradient on Alfalfa Silage Quality, Odor, and Bacterial Community Revealed by Electronic Nose and GC-MS. [PDF]

Microorganisms
Liu Y, Wang Z, Sun L, Zhang Y, Zhao M, Hao J, Liu M, Ge G, Jia Y, Du S.   +9 more
europepmc   +1 more source

Electrochemical cyclization of alkynes to construct five-membered nitrogen-heterocyclic rings. [PDF]

Beilstein J Org Chem
Peng L, Wang T, Yuan Z, Li B, Tang Z, Liu X, Li H, Jiang G, Zeng C, Wong HNC, Peng XS.   +10 more
europepmc   +1 more source

Heterocyclic steroids: Efficient routes for annulation of pentacyclic steroidal pyrimidines

Steroids, 2020
Steroids are components of cell membranes, signaling molecules and are a type of secondary metabolites as a result of their high impact of biological significance. The present review described the literature reports of pentacyclic steroidal pyrimidines as a type of heterocyclic steroids.
M. Monier, Ahmed El-Mekabaty, Doaa Abdel-Latif, Başak Doğru Mert, Khaled M. Elattar   +4 more
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Heterocyclic Steroids

2023
Steroids are organic compounds with four rings arranged in a precise molecular configuration and are involved in many biological functions displaying a wide spectrum of biological activities and diverse chemical reactivities. Structural modifications of the steroidal rings have attracted a considerable amount of attention recently.
Mukesh M. Mudgal, Mangesh M. Mudgal
openaire   +1 more source

Heterocyclic steroids. Steroidal pyrimidines

Experientia, 1963
Die erste Synthese eines Steroid-Analogen, in welchem Ring A zu einem Pyrimidin umgewandelt wurde, wird beschrieben. Die wichtigste Zwischenstufe 4b wurde durch Abbau von 19-nor-Testosteron gewonnen. Kondensation von 4b mit Thioharnstoff fuhrte zu 17β-Acetoxy-2,4-diazaestr-4-en-1-on-3-thion (5).
E, CASPI, D M, PIATAK
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Heterocyclic steroids VII

Tetrahedron Letters, 1966
Abstract The acetylester (Ib) has been transformed into several derivatives. The direction of bromination of the 4-ketone under acid conditions has been shown as proceeding toward C-3 by the isolation of bromosteroids (Ic) and V. In addition, the 2-oxa lactone (III) has been prepared.
J.G. Westra, W.N. Speckamp, U.K. Pandit, H.O. Huisman   +3 more
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Heterocyclic steroids V. 2,4-diaza steroids

Steroids, 1964
Abstract A new route to methyl 17β-acetoxy-1,5-seco-2,3,4-trisnorestr-5-one-1-oate has been developed. This β-ketoester has been used for the synthesis of steroidal pyrimidines.
D.M. Piatak, E. Caspi
openaire   +1 more source

Polynuclear heterocyclic systems. Part V: Heterocycles related to steroids and C‐nor‐steroids

Recueil des Travaux Chimiques des Pays-Bas, 1968
AbstractThe preparation of 6‐methoxy‐2‐(2′‐oxocyclopentyl‐1‐tetralone (I) and 2‐(2′‐oxocyclopentyl)quinolizidin‐1‐one (II) is described. Diketones I and II have been converted to heterocyclic systems related to steroids and C‐nor‐steroids.
R. van Hes, S. Skolnik, U. K. Pandit, H. O. Huisman   +3 more
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Total synthesis of heterocyclic steroids

J. Chem. Soc., Perkin Trans. 1, 1983
The total synthetic approach developed initially for natural steroids, and used for the preparation of A-nor compounds, has been extended to the preparation of novel heterocyclic steroids. The easily accessible 3,4-dinor-2,5-seco-9α-estrane-1,5,17-trione (9a) was treated with hydrazine hydrate, urea, and hydroxylamine hydrochloride to provide the 1 ...
Yu Ding, Bahman Nassim, Pierre Crabbé
openaire   +1 more source