RESUMO
Although progress has been made in enantioselective hydroboration of di- and trisubstituted alkenes over the past decades, enantioselective hydroboration of tetrasubstituted alkenes with high diastereo- and enantioselectivities continues as an unmet challenge since the 1950s due to its extremely low reactivity and the difficulties to simultaneously control the regio- and stereoselectivity of a tetrasubstituted alkene. Here, we report highly regio-, diastereo-, and enantioselective catalytic hydroboration of diverse acyclic tetrasubstituted alkenes. The delicate interplay of an electron-rich rhodium complex and coordination-assistance forms a highly adaptive catalyst that effectively overcomes the low reactivity and controls the stereoselectivity. The generality of the catalyst system is exemplified by its efficacy across various tetrasubstituted alkenes with diverse steric and electronic properties.
RESUMO
OBJECTIVE: To investigate the expressions of transforming growth factor-beta(1) and Smad4 in the prostatic tissue of rat models of chronic nonbacterial prostatitis (CNP), and to explore the mechanisms of CNP and its fibrosis. METHODS: Sixty 6-month-old SD rats were randomly allocated into three groups of equal number: normal control, 30 d CNP model and 45 d CNP model, the models made by castration + high-dose intramuscular injection of estradiol benzoate. The expressions of TGF-beta1 and Smad4 in the prostatic tissue were detected by immunohistochemistry and Western blot. RESULTS: Compared with the normal controls, the 30 d and 45 d CNP rat models showed a significantly increased expression of TGF-beta1 and decreased expression of Smad4 (P < 0.05), even more significantly in the 45 d than in the 30 d group. And the expression of TGF-beta1 was negatively correlated with that of Smad4 in the CNP rat models. CONCLUSION: TGF-beta1 and Smad4 may be involved in the pathogenesis of CNP, and prostatic fibrosis may make the condition difficult to cure.