ABSTRACT
In order to study the impact of regioisomeric diene ligands on the formation and catalytic activity of Rh complexes, a series of C2- and CS-symmetric 2,5-disubstituted bicyclo[3.3.0]octa-2,5-dienes C2-L and CS-L, respectively, were synthesized from Weiss diketone by simultaneous deprotonation/electrophilic trapping of both oxo functions, and the catalytic behavior was studied in the presence of [RhCl(C2H4)2]2. Complexes [RhCl(C2-L)]2 bearing C2-symmetric ligands catalyzed effectively the asymmetric arylation of N-tosylaldimines to (S)-diarylamines with yields and ee values up to 99%. In Hayashi-Miyaura reactions, however, the complexes showed poor catalytic activity. When complexes [RhCl(CS-L)]2 with CS-symmetric ligand or mixtures of [RhCl(C2-L)]2 and [RhCl(CS-L)]2 were employed in 1,2-additions, racemic addition products were observed, suggesting a CâC isomerization of the diene ligands. X-ray crystal structure analysis of both Rh complexes formed from the [RhCl(C2H4)2]2 precursor and ligands C2-L and CS-L revealed that only the C2-symmetric ligand C2-L coordinated to the Rh, whereas CS-L underwent a Rh-catalyzed CâC isomerization to rac-C2-L, which then gave the racemic [RhCl(rac-C2-L)]2 complex. DFT calculations of the relative stabilities of the Rh complexes and the proposed intermediates provided a mechanistic rationale via Rh-mediated hydride transfer.
ABSTRACT
BACKGROUND: As many sufferers from phobic and panic (phobia/panic) disorders cannot get to suitable therapists, routine aspects of therapy were delegated to internet-accessed computer-aided self-help with or without exposure instructions. METHODS: Phobia/panic referrals were randomised to computer-aided self-help via the internet at home in a 2:1 ratio either by self-exposure cognitive behaviour therapy (CBT) [FearFighter (FF), n = 45] or by minimal CBT without exposure [Managing Anxiety (MA), n = 23]. All had brief backup phone advice from a clinician concerning their computer guidance. RESULTS: On self-ratings and blinded assessor ratings, patients improved equally with each form of self-help over 10 treatment weeks but significantly more on 5 out of 10 measures by week 14 (1-month follow-up) when the self-help included self-exposure instructions than when it did not. In accord with this, standardised effect sizes (Cohen's d) indicated superiority of FF over MA on 5 measures by week 14. Satisfaction with treatment in all patients pooled correlated positively with improvement after treatment and at 1-month follow-up. CONCLUSIONS: At the end of treatment, computer-aided CBT self-help at home via the internet plus brief live helpline support was effective with or without exposure instructions, and at 1-month follow-up it was more effective on some measures if exposure instructions had been included. Analysis is needed of how non-exposure CBT produced its shorter-term effect.
