Diastereoselective Conjugate Addition of Organocuprates to 3,4-Dimethyl-5,6-dihydro-2(1H)-pyridinones. A Concise Synthesis oftrans-3,4-Dimethyl-4-phenylpiperidines

Diastereoselective syntheses of (3R*,4R*)- and (3R*,4S*)-4-aryl-3-methyl-4-piperidinemethanol and fluoro analogues

Two concise and high-yielding diastereoselective syntheses of 4-aryl-3-methyl-4-piperidinemethanols were realized from 1,3-dimethyl-4-piperidinone. The key reactions to control the C3-C4 relative stereochemistry were the alkoxymethylation of a metalloenamine generated from 4-aryl-3-methyl-1,2,3,6-tetrahydropyridine that afforded the (3R*,4S*)-form and the nucleophilic substitution of a fluoroarene with deprotonated 3-methyl-4-piperidinenitrile giving the (3R*,4R*)-isomer. The corresponding fluoromethyl analogues were subsequently obtained through the fluorination of the piperidinemethanols using DAST.

Endogenous opiates and behavior: 2007

This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

First asymmetric synthesis of trans-3,4-dimethyl-4-arylpiperidines

The first asymmetric synthesis of the trans-3,4-dimethyl-4-arylpiperidine opioid antagonist scaffold is reported. C-3 stereochemistry was established via CBS reduction and stereoselective anti-SN2' cuprate displacement of the derived allylic phosphonate. The resultant vinyl bromide was then elaborated to the target compound by Suzuki coupling and trans-selective 4-methylation. Extension of this methodology should allow general enantioselective access to highly substituted piperidine ring systems.