The [W(CO)5]‐catalyzed cycloisomerization reaction of 1,1‐disubstituted 4‐pentyn‐1‐ol derivatives has been studied from both, an experimental and theoretical point of view. Three different catalytic systems have been evaluated {preformed [(thf)W(CO)5], [W(CO)6]/excess Et3N, and [W(CO)6]/2 mol % Et3N]. We have found that the reaction proceeds to give the formal endo‐ or exo‐cycloisomerization products depending on the amount of Et3N used and on the substitution along the alkyl chain of the starting alkynol. The theoretical study allowed us to find the mechanisms of the reactions which explain the formation of the formal endo‐ or exo‐cycloisomerization products.
The prevalence of infertility has increased significantly in recent years. The global prevalence of infertility is reported to be 10%-15% affecting approximately 10% of couples. The purpose of the study was to explore the causes of infertility among couples who visited the University Clinical Centre in Prishtina, Kosovo during the period of 2000-2010. Primary infertility was found in 229 (71.1%) couples and Secondary in 93 (28.9%) ones. Of the causes of infertility were: female factors in 127 (39.4%) of couples, male factors in 58 (18%), combined factors in 99 (30.7%) and unknown infertility in 38 (11.8%) of couples. In reviews of infertile couples, study of male and female factors is important and mostly the couples mentioned more than one reasons as the infertility factor. Finally, preconception care and counseling are recommended to all those who are planning a pregnancy to avoid failure.
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