Bismethylenedioxy group

A bismethylenedioxy group in a 4-chloro or 11-keto steroid is stable to cleavage by formic acid or glacial acetic acid (100°, 6 h). The tetramethyl derivative is readily hydrolyzed (50% AcOH, 90°, 3-4 h, 80-90% yield). ... 

Bile acids, steroids from, 188 Biperidin, 47 Birch, Arthur J., 163 Birch reduction, 163, 167, 170 Bishydroxycoumarin, 331 Bismethylenedioxy group, 193 Blocking agents, of B-sympathet-ic receptors, 65, 117... 

The bismethylenedioxy group (BMD) [ (49)] represents the most suitable protecting group for the dihydroxyacetone side chain of corticosteroids. This group is stable to lead tetraacetate, brief heating with hydrochloric acid in acetic acid,108 or with sulfuric acid in methanol18 and to Jones oxidation.189... 

The synthesis of novel corticoids possessing rings a and b in a 10(5 — 4t)abeo system has been described.In the simplest case, the corticoid (263) was used as starting material. The C-17-chain was converted into a bismethylenedioxy-group (BMD), after protection of the hydroxyl at C-11/3 as the fluoromethyl ether (264). Acid hydrolysis liberated the 11-alcohol (265). This with alkaline hydrogen... 

BMD bismethylenedioxy group LA(tBuO)3H lithium tri-t-butoxy aluminum... 

Hydroxyl groups are stable to peracids, but oxidation of an allylic alcohol during an attempted epoxidation reaction has been reported." The di-hydroxyacetone side chain is usually protected during the peracid reaction, either by acetylation or by formation of a bismethylenedioxy derivative. To obtain high yields of epoxides it is essential to avoid high reaction temperatures and a strongly acidic medium. The products of epoxidation of enol acetates are especially sensitive to heat or acid and can easily rearrange to keto acetates. 

Bismethylenedioxy protecting group, 190 p-Blockers, 41 Blood-brain barrier, 52,... 

Steroid bismethylenedioxy (BMD) derivatives. A Merck group found that on stirring 50 g. of cortisone (1) with chloroform (2 1.), formalin (0.5 1.), and coned, hydrochloric acid (0.5 1.) for 48 hrs., the hormone is converted into the crystalline BMD derivative (2, m.p. 258-261°). Other steroids having the highly sensitive... 

Miscellaneous.—Tetramethyl-bismethylenedioxy-derivatives (780) of the di-hydroxyacetone side-chain are readily prepared by the action of acetone and perchloric acid. As protecting groups they appear to have advantages over the well-known bismethylenedioxy-compounds, especially in being more readily hydrolysed. NJV-Dimethylhydrazones can be used to protect oxo-groups, during oxidation, reduction, hydroboronation, hydrolysis, etc., elsewhere in the molecule. 

Miscellaneous Reactions.—Trity fluoroborate. previously reported as cleaving acetals by hydride abstraction, also cleaves benzylic ethers and a variety of related species, giving benzaldehydes. " Cholesteryl benzyl ethers afford cholesterol. The bismethylenedioxy protecting group for the corticosteroid side-chain is also cleaved with this reagent. 

Replacement of one or both dimethoxy groupings with methylenedioxy groups slightly decreased the antileukemic activity. However, the 8-methyl and ethyl bismethylenedioxy analogs showed KB activity in cell culture, whereas the corresponding bis(dimethoxy) compounds did not. 

Steroidal alcohols, masked as their tetrahydropyranyl ethers, benzyl ethers or bismethylenedioxy-derivatives, can be deprotected by the trityl carbonium ion in a hydride-transfer process. This method of regeneration should be equally applicable to other protected groups such as amines and carboxylic acids. 

Makhubu, L. P., Z. G. Hajos, and G. R. Duncan Selective Hydrolysis and Oxidation of the Bismethylenedioxy Protective Group During Angular Methyl Migration in Corticosteroid Analogs. Canad. J. Chem. 52, 1744 (1974). 

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