Coumarins and related compounds. Part IV. Aluminium chloride-catalysed reaction of phenols with methyl acrylate: a new approach to the synthesis of hydroxycoumarins

Author(s):  
Arun K. Das Gupta ◽  
Rabindra M. Chatterje ◽  
Kaustubh R. Das ◽  
Brian Green
2003 ◽  
Vol 1 (7) ◽  
pp. 1133-1138 ◽  
Author(s):  
Perry T. Kaye ◽  
Musiliyu A. Musa ◽  
Xolani W. Nocanda ◽  
Ross S. Robinson

2012 ◽  
Vol 23 (3) ◽  
pp. 265-275 ◽  
Author(s):  
Renata Los ◽  
Marta Wesołowska-Trojanowska ◽  
Anna Malm ◽  
Monika M. Karpińska ◽  
Joanna Matysiak ◽  
...  

1989 ◽  
Vol 67 (6) ◽  
pp. 1032-1037 ◽  
Author(s):  
Thomas G. Back ◽  
Kurt Brunner ◽  
M. Vijaya Krishna ◽  
Enoch K. Y. Lai

(22S,23E)-6β-Methoxy-3α,5-cyclo-5α-ergost-23-en-22-ol (2), an intermediate in the synthesis of brassinolide (μ) and related compounds, was synthesized by a new approach. (20S)-6β-Methoxy-3α,5-cyclo-5α-pregnane-20-carboxaldehyde (5) was converted to the corresponding 22S and 22R-24-yn-22-ol derivatives 6a and 6b by treatment with 3-lithio-1 -trimethylsilylpropyne, followed by tetra-n-butylammonium fluoride. The products were subjected to selenosulfonation, base-catalyzed isomerization, and selenoxide elimination to afford the respective 22S and 22R allenic sulfones 9a and 9b. The 22S isomer 9a underwent addition with lithium diisopropylcuprate – dimethyl sulfide complex, followed by reductive desulfonylation with magnesium in methanol, to afford 2, as well as smaller amounts of its 24(28) isomer 11a and (22E)-6β-methoxy-3α,5-cyclo-5α-ergosta-22,24(28)-diene (12). Similar treatment of 9b afforded 13, the 22R isomer of 2, as the principal product, as well as its 24(28) isomer 11b, and diene 12. Keywords: brassinolide, (22S,23E)-6β-methoxy-3α,5-cyclo-5α-ergost-23-en-22-ol, selenosulfonation, allenic sulfones.


Heterocycles ◽  
1987 ◽  
Vol 25 (1) ◽  
pp. 157 ◽  
Author(s):  
Csaba Sz�tay ◽  
Lajos Szab� ◽  
P� Kolonits ◽  
Gy嗷gy Kalaus ◽  
Alajos K�m� ◽  
...  

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