Selective Deprotection of Methylene Acetal and MOM Ether in the Presence of Ketal-Type Protective Groups: Remarkable Effect of TBSOTf
摘要:
A novel procedure for highly selective deprotection of methylene acetals and MOM (methoxymethyl) groups in the presence of ketal-type protective groups has been developed. The method, which utilizes a combination of TBSOTf and 2,2'-bipyridyl, displays a completely opposite selectivity compared with those of acid-mediated deprotection protocols.
Conversion of Epoxides to 1,3-Dioxolanes Catalyzed by Tin(II) Chloride
摘要:
Anhydrous tin(II) chloride is an efficient catalyst for the reaction of epoxides with acetone to prepare 2,2-dimethyl-1,3-dioxolanes (acetonides) in good to excellent yields. Mono-, di-, and trisubstituted epoxides participate equally well in this diastereospecific reaction. The use of single enantiomer epoxides under the reported conditions results in significant erosion of optical activity.