tag:blogger.com,1999:blog-51846086760422068.post8705682692199323289..comments2024-03-22T05:29:38.457-07:00Comments on Open Flask: The Recipe!BaranLabhttp://www.blogger.com/profile/01806245988209508968noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-51846086760422068.post-9711055602099643902014-11-17T08:40:05.478-08:002014-11-17T08:40:05.478-08:00That's great!!!Thanks BHH.That's great!!!Thanks BHH. dthhttps://www.blogger.com/profile/03933778988843986515noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-13611111633959276812014-11-15T11:00:06.376-08:002014-11-15T11:00:06.376-08:00Thanks for taking the time to provide a detailed a...Thanks for taking the time to provide a detailed answer. If you don't mind, I'd like to highlight this work on my blog sometime in the near future. The blog focuses on the synthetic chemistry and pharmacology of steroids. I'm at: http://modernsteroid.blogspot.com. Best, Brian.BHHhttps://www.blogger.com/profile/17674787259534472941noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-59458035459327251722014-11-13T10:14:12.052-08:002014-11-13T10:14:12.052-08:00Thanks for you interest BHH. You're right, it...Thanks for you interest BHH. You're right, it's a electron sink so whatever single electron reductants we used (metals like Pd(0), Ni(0), or tBuMgCl) resulted in C10-C9 cleavage A ring aromatization. In addition, two electron reductants like NaBH4, LAH resulted in C10-C19 bond cleavage A ring aromatization. So it is thermodynamically unfavorable. Furthermore, some simple calculations reveals that C9-C19 bond doesn't overlap with the C11 carbonyl pi-system (C ring), so it's not going to weaken even if we could selectively activate C11 ketone. As you've commented, I also think that changing the conformation of A ring is the key for the C9-C19 bond cleavage, we have some plans to do it including making a more saturated A-ring, protect A ring in a form of acetal but I haven't successfully made the substrates.dthhttps://www.blogger.com/profile/03933778988843986515noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-90165218114669390542014-11-12T18:07:09.008-08:002014-11-12T18:07:09.008-08:00Nice work, Hai! With regard to the C9-C19 bond cle...Nice work, Hai! With regard to the C9-C19 bond cleavage, can you comment on the impact of the oxidation state of the A-ring to the cyclopropane fragmentation? The A-ring dienone is a pretty good electron sink that provides a driving force for the undesired fragmentation with concomitant A-ring aromatization. Did you evaluate substrates that contained a saturated A-ring and retained the ketone at C11?BHHhttps://www.blogger.com/profile/17674787259534472941noreply@blogger.com