Efficient synthesis of N-oxysulfonyl formamidines through thionyl chloride-promoted reaction of sulfamates with formamides

N-Oxysulfonyl formamidine derivatives have been efficiently synthesized under mild conditions through direct condensation of various sulfamates and formamides in the presence of thionyl chloride. The scope of this reaction was investigated, and a plausible mechanism was proposed. The resulting N-oxysulfonyl formamidines can be converted to sulfamates through appropriate deprotection.     

Sustainable,mild and efficient p-methoxybenzyl ether deprotections utilizing catalytic DDQ

A procedure for the selective deprotection of p-methoxybenzyl ethers using catalytic amounts of DDQ and of sodium nitrite, with oxygen as the terminal oxidant, is reported.     

OXIDATIVE DEPROTECTION OF TRIMETHYLSILYL ETHERS WITH HEXAMETHYLENETETRAMINEBROMINE SUPPORTED ONTO SILICA GEL UNDER MICROWAVE IRRADIATION IN SOLVENTLESS SYSTEM

Hexamethylenetetramine-bromine supported onto[3pc] silica gel rapidly converts trimethylsilyl ethers to their corresponding carbonyl compounds under microwave irradiation in solventless system.     

Synthesis of 1-p-Methoxyphenyl and 1-p-Methoxyphenyl-4-methylbicyclo-[2.2.1]heptan-7-one. The Oxidation of 7-Hydroxy-1-p-methoxyphenyl-4-methylbicyclo[2.2.1]heptan-7-carboxylic Acid with Lead Tetraacetate

A simple synthetic route to 1-p-methoxyphenyl and 1-p-methoxyphenyl-4-methylbicyclo [2.2.1]heptan-7-one 6b,a has been developed through benzilic acid rearrangement of the bicyclo[2.2.1]octandiones 2b,a. The oxidation of 7-hydroxy-1-p-methoxyphenyl-4-methylbicyclo[2.2.1]heptan-7-carboxylic acid 3a with lead tetraacetate gives the carbolactone 7a which is also formed by the reaction of the ketone 6a with m-chloroperbenzoic acid.     

A Convenient One-Pot Synthesis of Symmetric Secondary and Tertiary Vicinal Diamines

A convenient one-pot synthesis of symmetric vicinal diamines utilizing sodium borohydride/trifluoroacetic acid reduction methodology is described .     

Rapid,Acid‐Mediated Deprotection of Silyl Ethers Using Microwave Heating

Microwave heating of triethylsilyl (TES)‐ and tert‐butyldimethylsilyl (TBS)‐protected 1° and 2° alcohols in a mixture of equal parts acetic acid, tetrahydrofuran (THF), and water allows deprotection in as little as 5 min. tert‐butyldiphenylsilyl (TBDPS)‐ and triisopropylsilyl (TIPS)‐protected alcohols and silyl‐protected phenols are stable in these conditions. Thus, selective deprotection of TES‐ and TBS‐protected alcohols in the presence of TIPS or TBDPS ethers is possible. Similarly, alkyl silyl ethers can be deprotected in the presence of aryl silyl ethers.     

Chemoselective Protection of Hydroxyl Groups and Deprotection of Silyl Ethers

Summary.  Trimethylsilylation of alcohols and phenols is carried out using hexamethyldisilazane and LiClO₄ under microwave irradiation and neutral conditions. The deprotection of silyl ethers is carried out similarly using natural kaolinitic clay and a few drops of water. Received March 1, 2001. Accepted (revised) April 17, 2001     

Catalyst-free water-mediated N-Boc deprotection

A catalyst-free water-mediated N-Boc deprotection of N-Boc-amines is reported. In the absence of any additional reagents, the free amines were formed from a variety of aromatic and aliphatic N-Boc-amines as well as from some N-Boc-amino acid derivatives.     

The fate of the tert-butylsulfinyl auxiliary after acid-promoted cleavage—a method for recycling t-BuSONH2

Ellman’s chiral auxiliary is converted into tert-butylsulfinyl chloride on sulfinamide deprotection with HCl and can be recovered in high yield upon treatment with ammonia. The enantiopure auxiliary can be obtained by trapping the sulfinyl chloride with a chiral alcohol followed by treatment of the resulting sulfinate ester with LiNH₂.