A concise effective deprotection of spiro 3-cyclic thiaza ketal of steroidal 1,4-dien-3-one.
An effective deprotective method of spiro 3-cyclic thiaza ketal of steroidal 1,4-dien-3-ones using alkyl vinyl ether in the presence of protic acid followed by the treatment of aqueous alkali was described. This novel protocol could be fulfilled under mild condition with high yield. The mechanism mediated by a carbonium ion formed in situ was clarified by the capture of the cleaved fragment.
Zhang
Bei Na
BN
Department of Medicinal Chemistry, Pharmacy School, Fudan University, Yi Xue Yuan Road 138, Shanghai 200032, China.
Chen
Ying
Y
Zhang
Qian
Q
Xia
Peng
P
D002384:Catalysis; D002626:Chemistry, Pharmaceutical / Q000379:methods; D004355:Drug Stability; D007202:Indicators and Reagents / Q000737:chemistry*; D015394:Molecular Structure; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013256:Steroids / Q000138:chemical synthesis* / Q000737:chemistry
D007202:Indicators and Reagents; D013141:Spiro Compounds; D013256:Steroids