In:
Collection of Czechoslovak Chemical Communications, Institute of Organic Chemistry & Biochemistry, Vol. 64, No. 2 ( 1999), p. 329-347
Abstract:
Depending on the conditions and the acid employed, 18β,19β-epoxy-28-hydroxy- 21-oxolupan-3β-yl acetate ( 2a ) and 18β,19β-epoxy-21-oxolupane-3β,28-diyl diacetate ( 2b ) on treatment with acid gave three types of products: (i) 28-nor derivatives: 21-oxo-28-norlupa-16,18-dien-3β-yl acetate ( 6 ), 19β-hydroxy-21-oxo-28-norlup-17-en-3β-yl acetate ( 7 ) and 17ξ-hydroxy-21-oxo-28-norlup-18-en-3β-yl acetate ( 8 ), (ii) lupa-12,18-dien-21-ones 4a and 4b , and (iii) 22β-substituted lup-18-en-21-one derivatives of the type 5 . The formation of 22β-substituted derivatives of the type 5 probably proceeds in the enol form of epoxy ketone 2 . Opening of the epoxide ring with shift of the double bond to position 19(21) and attack by nucleophilic species at C-22 followed by elimination of water and re-formation of the 22-oxo group leads to derivatives of the type 5 .
Type of Medium:
Online Resource
ISSN:
0010-0765
,
1212-6950
DOI:
10.1135/cccc19990329
Language:
English
Publisher:
Institute of Organic Chemistry & Biochemistry
Publication Date:
1999
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