First synthesis and characterization for the stereoisomers of Ulipristal acetate
The three stereoisomers, 11α,17α-isomer I, 11α,17β-isomer II and 11β,17β-isomer III are related substances of the selective progesterone receptor modulator Ulipristal acetate. Herein, we presented an efficient and practical synthesis approach to deliver these three stereoisomers for the first time, and also confirmed the structure of the key intermediate 5a by single-crystal X-ray analysis. Our research will be of immense help for organic chemists to study the impurity profile of Ulipristal acetate.
A simple and convenient synthetic route to Ulipristal acetate
We set out to describe a new and efficient route for preparing Ulipristal acetate with a good yield. The selected epoxidization conditions gave out 80% of 5α,10α-epoxide 2a in the two diastereoisomers which greatly improved the yield of 11β-substituted isomer 4a. And phenyl-sulfinyl compound 6 was synthesized from ketone 5 directly treated with phenylsulfenyl chloride in the presence of triethylamine. These synthetic procedures is only 8 steps, less than currently reported in the literature, but more suitable for industrial process.
Advance Provision of Emergency Contraception for Pregnancy Prevention: A Meta-Analysis
OBJECTIVE: Advance provision of emergency contraception can circumvent some obstacles to timely use. We performed a meta-analysis to summarize randomized controlled trials evaluating advance provision of emergency contraception to explore effects on pregnancy rates, sexually transmitted infections, and sexual and contraceptive behaviors. DATA SOURCES: In August 2006, we searched CENTRAL, EMBASE, POPLINE, MEDLINE, a specialized emergency contraception article database, and contacted experts to identify published or unpublished trials. METHODS OF STUDY SELECTION: We included randomized controlled trials comparing advance provision to standard access, defined as any of the following: counseling (with or without information about emergency contraception) or provision of emergency contraception on request at a clinic or pharmacy. TABULATION, INTEGRATION AND RESULTS: Two reviewers independently assessed study quality. We performed a meta-analysis using Review Manager software. Eight randomized controlled trials met inclusion criteria, representing 6,389 patients in the United States, China, and India. Advance provision did not decrease pregnancy rates, despite increased use (single use, odds ratio [OR] 2.52, 95% confidence interval [CI] 1.72–3.70; multiple use: OR 4.13, 95% CI 1.77–9.63) and faster use (weighted mean difference –14.6 hours, 95% CI –16.77 to –12.4 hours). Advance provision did not increase rates of sexually transmitted infections (OR 0.99, 95% CI 0.73–1.34), unprotected intercourse, or changes in contraceptive methods. Women who received emergency contraception in advance were as likely to use condoms as other women. CONCLUSION: Advance provision of emergency contraception did not reduce pregnancy rates and did not negatively affect sexual and reproductive health behaviors and outcomes compared with conventional provision. LEVEL OF EVIDENCE: III