Thomas J. Blacklock

Mild and regioselective oxidative bromination of anilines using potassium bromide and sodium perborate

Abstract The selective monobromination of various deactivated anilines using potassium bromide and sodium perborate as oxidant has been achieved. The use of ammonium molybdate as catalyst accelerates the rate of reaction but is not essential to obtain good yields and high selectivities.

DABCO- and DBU-accelerated green chemistry for N-, O-, and S-benzylation with dibenzyl carbonate

Abstract An environmentally friendly process for the benzylation of nitrogen, oxygen, or sulfur atoms with dibenzyl carbonate has been developed. Catalytic amounts of DABCO or DBU can accelerate this ‘green’ alkylation.

ASYMMETRIC SYNTHESIS OF 3,5-DIHYDROXY-6(E)-HEPTENOATE-CONTAINING HMG-COA REDUCTASE INHIBITORS

Abstract A ‘one-pot’ conversion of aldehyde 6 to hydroxyketoester 10 with high enantioselection, culminating in a practical asymmetric synthesis of (3 R ,5 S ) isomer of the antihyperlipoproteinemic agent fluvastatin, 1 , is described. All four 3,5-dihydroxy-6( E )-heptenoate stereoisomers were prepared in enantiopure form starting from 10 , utilizing selective reduction and oxidation methods.

Selective deprotection of alkyl t-butyldimethylsilyl ethers in the presence of aryl t-butyldimethylsilyl ethers with bismuth bromide

Abstract Alkyl t -butyldimethylsilyl ethers can be selectively cleaved in the presence of aryl ethers using a catalytic amount of bismuth bromide in wet acetonitrile at ambient temperatures.

A mild method for ring-opening aminolysis of lactones

Abstract A mild and general method for lactone aminolysis is reported. Sodium 2-ethylhexanoate (NaEH) is found to serve both as a base and a catalyst in aminolysis of a variety of lactones by benzylamine hydrochloride. The nearly neutral pH conditions make this method applicable to many acid/base sensitive substrates.

A practical synthesis of enantiopure ethyl cis-2-amino-1-cyclohexanecarboxylate via asymmetric reductive amination methodology

Abstract A simple and practical method for large scale preparation of optically pure ethyl 2-amino-1-cyclohexanecarboxylate was developed via a reductive amination of 2-oxo-cyclohexanecarboxylate with a chiral α-methylbenzylamine. The major diastereomer was isolated in optically pure form by a simple and efficient crystallization as its HBr salt. The diastereoselectivity as well as the cis trans selectivity was also improved.

A convenient and practical method for N-acylation of 2-oxazolidinone chiral auxiliaries with acids

Abstract A one-pot, convenient and practical method for N-acylation of 2-oxazolidinone chiral auxiliaries directly with acids in the presence of pivaloyl chloride and triethylamine is described.

The enantioselective reduction of 2'-fluoroacetophenone utilizing a simplified CBS-reduction procedure

Abstract We have developed a practical, non-enzymatic, catalytic process for the enantioselective reduction of 2′-fluoroacetophenone. A number of catalysts were screened for the oxazaborolidine-type reduction of this ketone to obtain an optimized system. We have shown that the simplest procedure uses the catalyst formed in situ from ( S )-α,α-diphenyl-2-pyrrolidinemethanol (( S )- 2 ) and borane–diethylaniline.

Double Heck reaction of bridged o, o'-dibromobiaryls with ethyl acrylate

Abstract An inter- followed by an intramolecular double Heck reaction of bridged o,o′-dibromobiaryls with ethyl acrylate is described. The nature of the bridging atom/group determined the outcome of the reaction. This double Heck reaction strategy afforded a safe and convenient synthesis of 9-(ethoxycarbonylmethylene)-9H-xanthene and a novel route to 9 and/or 10-substituted anthracene derivatives.

In-situ generation of Et3SiBr from BiBr3 and Et3SiH and its use in preparation of dialkyl ethers

Abstract The reported BiBr 3 –Et 3 SiH catalyzed reductive etherifications of silyl ethers with carbonyl compounds are shown to be catalyzed by the in situ formed Et 3 SiBr and verified by an independent use of the commercial reagent. As Et 3 SiBr is moisture sensitive and is not readily available, this in situ generation is still recommended as the method of choice. Utilizing this method, several alcohols were transformed under very mild conditions into dialkyl ethers via their silyl intermediates, such as TES, TBDMS, and TIPS.