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1.
Proc Natl Acad Sci U S A ; 104(43): 16787-92, 2007 Oct 23.
Article in English | MEDLINE | ID: mdl-17942689

ABSTRACT

We describe highly enantioselective synthesis of beta-amino acid derivatives (1a-c) using asymmetric hydrogenation of alpha-aminomethylacrylates (2a-c), which contain a free basic N H group, as the key step. The alpha-aminomethylacrylates (2a-c) were prepared using the Baylis-Hillman reaction of an appropriate aldehyde with methyl acrylate followed by acetylation of the resulting allylic alcohols (4a-b) and S(N)2'-type amination of the allylic acetates (3a-b).


Subject(s)
Amino Acids/chemical synthesis , Methacrylates/chemistry , Methacrylates/chemical synthesis , Catalysis , Hydrogenation , Stereoisomerism
2.
J Org Chem ; 68(5): 1954-7, 2003 Mar 07.
Article in English | MEDLINE | ID: mdl-12608816

ABSTRACT

DABCO is an extremely active catalyst for the methylation of indoles in conjunction with dimethyl carbonate (DMC). This green chemistry is highly effective and produces N-methylindoles in nearly quantitative yields. The reaction sequence consists of competing alkylation and acylation pathways and involves 1,4-diazabicyclo[2.2.2]octane (DABCO) dually as a nucleophilic catalyst, ultimately resulting in a single product: the N-methylated indole.

3.
Org Lett ; 5(2): 125-8, 2003 Jan 23.
Article in English | MEDLINE | ID: mdl-12529121

ABSTRACT

[reaction: see text] An efficient and practical N-methylation of amino acid derivatives with dimethyl sulfate in the presence of sodium hydride and a catalytic amount of water is described. Reaction of water with sodium hydride generated highly reactive dry sodium hydroxide, which led to much faster reaction rates than powdered sodium hydroxide itself.


Subject(s)
Amino Acids/chemical synthesis , Methylation , Sodium Hydroxide/chemistry , Sulfuric Acid Esters/chemistry , Water/chemistry
4.
J Org Chem ; 67(19): 6612-7, 2002 Sep 20.
Article in English | MEDLINE | ID: mdl-12227788

ABSTRACT

An efficient and large-scale enantioselective synthesis of PNP405 (1), a purine nucleoside phosphorylase inhibitor, is described. This synthesis of 1 involved eight steps starting from o-fluorophenylacetic acid with a 21.6% overall yield and >99.5% enantiopurity. The key stereogenic center with (R)-configuration was created using Evans' asymmetric alkylation methodology. This synthesis also features the racemization-free reductive removal of the chiral auxiliary in 5 using sodium borohydride, protection of the gamma-cyano alcohol 6 as the trityl ether by a new water-assisted tritylation with trityl chloride and triethylamine or with trityl alcohol and catalytic trifluoroacetic acid, and an efficient one-pot cyclo-guanidinylation of 10 using cyanamide as the guanidinylating agent.


Subject(s)
Combinatorial Chemistry Techniques/methods , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Fluorobenzenes/chemical synthesis , Fluorobenzenes/pharmacology , Purine-Nucleoside Phosphorylase/antagonists & inhibitors , Pyrimidinones/chemical synthesis , Pyrimidinones/pharmacology , Catalysis , Enzyme Inhibitors/chemistry , Fluorobenzenes/chemistry , Molecular Structure , Pyrimidinones/chemistry , Stereoisomerism
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