Stereoselective total synthesis of testosterone and androsterone viaA/B-ring construction of the steroidal ring system by intramolecular Diels–Alder reaction

1986 ◽  
pp. 117-123 ◽  
Author(s):  
Masataka Ihara ◽  
Izumi Sudow ◽  
Keiichiro Fukumoto ◽  
Tetsuji Kametani
Keyword(s):  
Total Synthesis ◽  
Alder Reaction ◽  
Ring System ◽  
Diels Alder ◽  
Diels Alder Reaction

scholarly journals Crystal structures and conformations of two Diels–Alder adduct derivatives: 1,8-bis(thiophen-2-yl)-14-oxatetracyclo[6.5.1.02,7.09,13]tetradeca-2(7),3,5-trien-10-one and 1,8-diphenyl-14-oxatetracyclo[6.5.1.02,7.09,13] tetradeca-2,4,6-trien-10-one

2015 ◽  
Vol 71 (2) ◽  
pp. 213-216
Author(s):  
S. Gopinath ◽  
P. Narayanan ◽  
K. Sethusankar ◽  
Meganathan Nandakumar ◽  
Arasambattu K. Mohanakrishnan
Keyword(s):  
Crystal Packing ◽  
Rotation Axis ◽  
Alder Reaction ◽  
Ring System ◽  
Diels Alder ◽  
Compound I ◽  
Diels Alder Reaction ◽  
Phenyl Rings ◽  
Axis Parallel ◽  
Alder Adduct

The title compounds, C21H16O2S2(I) and C25H20O2(II), are products of a tandem `pincer' Diels–Alder reaction consisting of [2 + 2] cycloadditions between benzo[c]furan and cyclopentanone. Each comprises a fused tetracyclic ring system containing two five-membered rings (inenvelopeconformations with the O atom as the flap) and six-membered rings (inboatconformations). In addition, two thiophene rings in (I) and two phenyl rings in (II) are attached to the tetracyclic ring system. The cyclopentanone ring adopts atwistedconformation in (I) and anenvelopeconformation in (II). In (I), the thiophene rings are positionally disordered over two sets of sites, with occupancy ratios of 0.901 (2):0.099 (2) and 0.666 (2):0.334 (2). In (II), the oxygen atom of the cyclopentanone ring is rotationally disordered over two sites with an occupancy ratio of 0.579 (4):0.421 (4). The molecular structure of (I) is stabilized by an intramolecular C—H...O hydrogen bond, which generates anS(7) ring motif. In the crystal, the molecules are linkedviaweak C—H...O hydrogen bonds, which generateR22(16) ring motifs in (I) andC(8) chains in (II). In both structures, the crystal packing also features C—H...π interactions. The crystal studied of compound (I) was twinned by non-merohedry. The twin component is related by the twin law [−1 0 0 −0.101 1 −0.484 0 0 −1] operated by a twofold rotation axis parallel to thebaxis. The structure of (I) was refined with a twin scale factor of 0.275 (2).

Catalytic Asymmetric Total Synthesis of (+)- and (−)-Paeoveitol via a Hetero-Diels–Alder Reaction

2017 ◽  
Vol 19 (3) ◽  
pp. 429-431 ◽  
Author(s):  
Tian-Ze Li ◽  
Chang-An Geng ◽  
Xiu-Juan Yin ◽  
Tong-Hua Yang ◽  
Xing-Long Chen ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Alder Reaction ◽  
Diels Alder ◽  
Asymmetric Total Synthesis ◽  
Diels Alder Reaction ◽  
Catalytic Asymmetric

Simple, efficient total synthesis of cantharidin via a high-pressure Diels-Alder reaction

1980 ◽  
Vol 102 (22) ◽  
pp. 6893-6894 ◽  
Author(s):  
William G. Dauben ◽  
Carl R. Kessel ◽  
Kazuo H. Takemura
Keyword(s):  
High Pressure ◽  
Total Synthesis ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction

Total synthesis of (±)-5β,8α- androst-9(11)-ene-3,17-dione

1979 ◽  
Vol 57 (24) ◽  
pp. 3354-3356 ◽  
Author(s):  
Masatoshi Kakushima ◽  
Leonard Allain ◽  
Robert A. Dickinson ◽  
Peter S. White ◽  
Zdenek Valenta
Keyword(s):  
Total Synthesis ◽  
Alder Reaction ◽  
Diels Alder ◽  
Allylic Alcohol ◽  
Diels Alder Reaction

A total synthesis of (±)-5β,8α- androst-9(11)-ene-3,17-dione is described. The key step is a ring C forming SnCl4-catalyzed Diels–Alder reaction in which the geometry of the diene controls syn–anti stereochemistry while the catalyst guides the addition to the desired endo orientation. A preparation of ethyl E-2-methyl-4-oxo-2-butenoate and the dehydration of a tertiary allylic alcohol by the pyrolysis of the corresponding tosyl carbamate are also described.

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