Nickel-catalyzed C-H arylation of azoles with haloarenes: scope, mechanism, and applications to the synthesis of bioactive molecules

Novel nickel-based catalytic systems for the C-H arylation of azoles with haloarenes and aryl triflates have been developed. We have established that Ni(OAc)(2)/bipy/LiOtBu serves as a general catalytic system for the coupling with aryl bromides and iodides as aryl electrophiles. For couplings with more challenging electrophiles, such as aryl chlorides and triflates, the Ni(OAc)(2)/dppf (dppf = 1,1'-bis(diphenylphosphino)ferrocene) system was found to be effective. Thiazoles, benzothiazoles, oxazoles, benzoxazoles, and benzimidazoles can be used as the heteroarene coupling partner. Upon further investigation, we discovered a new protocol for the present coupling using Mg(OtBu)(2) as a milder and less expensive alternative to LiOtBu. Attempts to reveal the mechanism of this nickel-catalyzed heterobiaryl coupling are also described. This newly developed methodology has been successfully applied to the syntheses of febuxostat (a xanthine oxidase inhibitor that is effective for the treatment of gout and hyperuricemia), tafamidis (effective for the treatment of TTR amyloid polyneuropathy), and texaline (a natural product having antitubercular activity).

Influence of pregnancy on the evolution of background retinopathy. Preliminary results of a prospective fluorescein angiography study

Previous reports have suggested that pregnancy does not influence the development of diabetic retinopathy. Since 1979 a prospective study using fluorescein angiography has been in progress. Preliminary results include 22 diabetic women with or without moderate background retinopathy studied until delivery. They were maintained under good metabolic control (mean HbA1: 7.68%). Five clinical and fluorescein angiography examinations were performed at prefixed intervals (before the 15th week, at the 28th and 35th weeks of pregnancy, and 6 and 15 months after delivery). The analysis of fluorescein angiography which did not induce any side effect showed that the mean number of microaneurysms increased from 42.7 before pregnancy to 56.7 at the 28th week and to 79.7 at the 35th week. Six months later the number was 62.7, and 15 months later 60.3, still higher than at the initial examination. This study suggests that pregnancy has an unfavourable influence on the background retinopathy in diabetic patients even when a good metabolic control is achieved and retinopathy is minimal.

Binding of 125I-insulin to the human histiocytic lymphoma cell line U-937: effect of differentiation with retinoic acid

The human histiocytic lymphoma line U-937 consists of cells having characters of immature monocytes. We have demonstrated that these cells possess highly specific insulin receptors with binding properties similar to that found for mature human blood monocytes. 125I-insulin binding increased progressively with time to reach a maximum at 90 min at 22 degrees C and was proportional to the number of cells in the incubation medium. Insulin degradation as assessed by TCA precipitation was negligible. Scatchard analysis of the binding data was curvilinear and the total number of insulin binding sites was around 13,500. The average affinity profile gave an 'unoccupied site' affinity constant of 1.34 nM-1. When the U-937 cells were induced to differentiate into morphologically and functionally monocyte-like cells, after incubation with retinoic acid, the total number of binding sites decreased significantly with no change in the affinity of the hormone for its receptor.

[Prevalence of smoking among diabetics and influence of tobacco on diabetic retinopathy]

Among 647 patent diabetics regularly followed who attended the out-patient clinic of a hospital Diabetology Department between December 1st, 1979 and June 30th, 1980, 35% were habitual smokers, 20% ex-smokers and 45% non-smokers. Insulin-treated diabetics did not smoke more than non insulin-treated diabetics. Only one-half of the smokers declared that they had been advised by a doctor to stop smoking. This study failed to demonstrate any effect of tobacco on the prevalence or severity of diabetic retinopathy.

[Effect of long-term administration of clonidine on growth hormone secretion in hypertensive diabetics]

The anti-hypertensive effect of clonidine is closely related to its central alpha-agonist action. In acute administration, the drug provokes a significant increase in the plasma concentrations of growth hormone (GH). In chronic administration, the effects of clonidine on GH secretion are not well documented. Clonidine was administered at a daily dose of 0,15 to 0,30 mg to 10 non-obese diabetic hypertensive male subjects for at least 3 months. Blood glucose and GH plasma concentrations were determined 15 times during the 24-hour cycle. Blood glucose and GH values recorded before the intake and after stopping the drug, in the basal state, after meals, after measured muscular exercise and during the first stage of sleep could be superimposed when on and off clonidine. The effects of prolonged administration of clonidine on GH secretion thus differ markedly from the effects of acute administration as in non diabetic subjects. The long-term use of clonidine does not induce a chronic increase of GH plasma concentrations which might worsen the evolution of the diabetic microangiopathy.

[Mediation by opioid peptides of anterior pituitary response to insulin-induced hypoglycemia (author's transl)]

A 1.6 mg dose of the specific opiate antagonist naloxone was administered to normal volunteers, either separately or in conjunction with insulin-induce hypoglycemia, in order to study the possible mediation by opioid peptides of the release of adrenocorticotrophin (ACTH), lipotropins (LPH), human growth hormone (GH) and prolactin (PRL). Administered separately, naloxone was associated with a significant fall in PRL levels (p less than 0.01), a significant and unexpected rise in GH levels (p less than 0.02), and a suppression of the circadian decrease of ACTH and LPH levels. The association of naloxone with insulin-induced hypoglycemia significantly reduced the PRL peak (p less than 0.05), did not affect the rise of GH and lowered the ACTH peak, without altering the LPH peak. These data suggest the existence of a positive opioid tone to PRL secretion, as well as an opioid peptide role in the PRL response to hypoglycemia. They argue against the likelihood of an opioid pathway in the GH response to hypoglycemia. Furthermore, the data favor a paradoxical effect of naloxone on ACTH release during insulin-induced hypoglycemia.

Rapid identification of diabetic patients with essential hypertension sensitive to acebutolol

The antihypertensive effect of 2,000 mg of acebutolol investigated with an acute 48 hr test in 60 diabetic and 60 non-diabetic in-patients with essential hypertension. In hypertensive diabetic patients, acebutolol was induced a significant fall in blood pressure similar to that observed in non-diabetics. The acute antihypertensive effect of acebutolol was not uniform in hypertensive subjects: a significant decrease of blood pressure was observed in 34 diabetics and 31 non-diabetic patients. Fifteen out of the 34 diabetic responders to the 48 hr test were treated by acebutolol alone for six months; a highly significant correlation between the acute and the chronic antihypertensive effect of the beta-blocker was observed. As long-term results paralleled those of the short-term experiment, acute acebutolol administration appears to be a rapid means to select hypertensive diabetics sensitive or resistant to betablockers. Plasma renin activity was not found to give, in hypertensive diabetics, a reliable predictive index of the response to acute administration of acebutolol.

[Long-term results of surgical hypophysectomy for diabetic retinopathy (author's transl)]

Between 1969 and 1974, ten insulin-dependent diabetic patients underwent surgical hypophysectomy for rapidly progressive proliferative retinopathy endangering sight. Six to 11 years later, the 7 patients who survived had useful visual acuity and were leading a normal life. The long-term results of hypophysectomy on the eye could be observed in this series of patients with exceptionally long follow up: oedema had subsided, haemorrhagic exsudates and newly formed retinal vessels had disappeared, and the retinal had become hypovascular. However, argon laser photocoagulation has now considerably reduced the indications of surgical hypophysectomy.

[A study of the knowledge of diabetics (author's transl)]

One hundred and forty five diabetics regularly attending a hospital clinic were submitted to a questionnaire assessing their knowledge of diabetes. The patients had previously been instructed in urine glucose analysis, insulin injections, diet and hypoglycaemic attacks. Despite this, they appeared to be neither better controlled nor more painstaking with their disease than before education. The replies to the questionnaire revealed that the patients had poor understanding of the symptoms and of the long-term complications of diabetes, of the criteria of good control, and of the proportion of carbohydrate in common food. Moreover, they held many fallacious ideas with regard to these concepts. The results suggest that although these diabetics had acquired sufficient knowledge to avoid the acute metabolic disturbances of diabetes and to lead a day-to-day existence with a minimum of harmful effects, they were not properly aware of the long-term consequences of diabetes and of the overall strategy for the good management of their disease. An improved educational strategy appears necessary to enable diabetics to take better care of themselves.