- A short total synthesis of (±)-epimeloscine and (±)-meloscine enabled by a cascade radical annulation of a divinylcyclopropane
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The first stereoselective synthesis of epimeloscine has been accomplished in 13 total steps with a longest linear sequence of 10 steps. The core of the synthesis takes only five steps, the key ones being acylation, stereoselective tandem radical cyclization of a divinylcyclopropane to make two rings, and group-selective ring-closing metathesis of the resulting divinylcyclopentane to make the last ring.
- Zhang, Hanmo,Curran, Dennis P.
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p. 10376 - 10378
(2011/08/05)
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- New synthetic technologies for the construction of heterocycles and tryptamines
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New synthetic methods for the construction of novel heterocycles and tryptamines are described. Thus, N-Boc anilines (I) are sequentially converted to heterocycles II ((3-(2-aminophenyl)pyrrolidin-3-ol) derivatives),III (substituted 2-oxo-1,2-dihydrospirobenzo[d][1,3]oxazine-4,3'-pyrrol idines), and VI (2-(4,5-dihydro-1H-pyrrol-3-yl)aniline) derivatives through a route involving t-BuLi induced ortho-metalation/ LaCl3 2LiCl metalexchange, reaction with N-Boc pyrrolidin-3-one (5), and subsequent deca rboxylative fragmentation. Labile intermediates VI are effectively converted to tryptamines Xa and Xb under controlled proticacidconditions.Inadditiontoprovidingexpedientaccesstothe2-oxo- 1,2-dihydrospirobenzo[d][1,3]oxazine-4,3'-pyrrolidines (III), the method is applicable to the synthesis of the corresponding 2-oxo-1,2-dihydrospirobenzo[d] [1,3]oxazine-4,3'-piperidine series of spirocycles (e.g., 42) and their precursors (3-(2-aminophenyl)piperidin-3-ol derivatives, e.g., 43) by using N-Boc-protected piperidin-3-one (40). Applications of the developed synthetic technologies to the synthesis of regioisomeric spirocycles 87 and 90, tryptamines 88 and 91, Corey's aspidophytine tryptamine (97), and efavirenz (1) are also described.
- Nicolaou, K. C.,Krasovskiy, Arkady,Majumder, Utpal,Trepanier, Vincent E.,Chen, David Y.-K.
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supporting information; experimental part
p. 3690 - 3699
(2009/09/24)
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- An expedient strategy for the synthesis of tryptamines and other heterocycles
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(Chemical Equation Presented) Making many from one: N-Boc-protected anilines are converted into an array of useful N-heterocycles and tryptamines through an expedient, cascade-based synthetic sequence involving ortho metalation and subsequent coupling wit
- Nicolaou,Krasovskiy, Arkady,Trepanier, Vincent E.,Chen, David Y.-K.
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supporting information; experimental part
p. 4217 - 4220
(2009/03/12)
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