The Pauson-Khand reaction was promoted by the addition of alkyl methyl sulfides. Among the sulfides, the ones having primary and secondary alkyl groups were more effective than those with tertiary alkyl groups. The intermolecular cyclization with simple alkenes makes the use of n-butyl methyl sulfide as the best method to carry out the stoichiometric Pauson-Khand reaction.

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Humans, monkeys, and other animals are considered to have the cognitive ability to use functional categories-that is, stimulus groups based on functional equivalence independent of physical properties. To investigate the underlying neural mechanisms of the use of functional categories, we recorded single-unit activity in the prefrontal cortex of monkeys performing a behavioral task in which the rule-dependent usage of functional category was needed to select an appropriate response. We found a neural correlate of functional categories on the single-neuron level and found that category information is coded independently of other task-relevant information such as rule and contingency information. Analysis of the time course of the information activation suggested that contingency information used for action selection is derived by integrating incoming category information with rule information maintained throughout a session. Such neural computation can be considered as the neural background of flexible behavioral control based on category and rule.

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Ökonomisch und praktisch sind neu entwickelte Reaktionsbedingungen für die Pauson‐Khand‐Reaktion, die den Befund nutzen, daß primäre Amine diese Reaktion beschleunigen. Im einen Fall werden mehr als drei Äquivalente Cyclohexylamin in 1,2‐Dichlorethan bei 83 °C verwendet und im anderen ein Gemisch aus 1,4‐Dioxan und 2 M wäßrigem NH3 (1/3, v/v) bei 100°C, Unter diesen Bedingungen ist z.B. die unten gezeigte Cyclisierung nach 5 bzw. 15 min vollständig abgelaufen, und das Produkt kann in 99 bzw. 93% Ausbeute isoliert werden.

A functional category is a set of stimuli that are regarded as equivalent independently of their physical properties and elicit the same behavioral responses. Major psychological theories suggest the ability to form and utilize functional categories as a basis of higher cognition that markedly increases behavioral flexibility. Vaughan claimed the category use in pigeons on the basis of partition, a mathematical criterion for equivalence, however, there have been some criticisms that the evidence he showed was insufficient. In this study, by using a group reversal task, a procedure originally used by Vaughan, we aimed to gather further evidence to prove the category use in animals. Macaque monkeys, which served as subjects in our study, could efficiently perform the task not only with familiar stimulus sets as Vaughan demonstrated but also with novel sets, and furthermore the task performance was stable even when the number of stimuli in a set was increased, which we consider as further evidence for the category use in animals. In addition, by varying the timing of the reversal, we found that a category formation takes place soon after encountering new stimuli, i.e. in a few blocks of trial after a novel stimulus set was introduced.

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