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Carbon–carbon bond formation is one of the most important tools in synthetic organic chemists’ toolbox. It is a fundamental transformation that allows synthetic chemists to synthesize the carbon framework of complex molecules from inexpensive simple starting materials. Among the many synthetic methodologies developed for the construction of carbon–carbon bonds, organocopper reagents are one of the most reliable organometallic reagents for this purpose. The versatility of organocuprate reagents or the reactions catalyzed by organocopper reagents were demonstrated by their applications in a variety of synthetic transformations including the 1,4-conjugate addition reactions. Sulfur-containing heterocyclic compounds are a much less studied area compared to oxygen-containing heterocycles but have gained more and more attention in recent years due to their rich biological activities and widespread applications in pharmaceuticals, agrochemicals, and material science. This paper will provide a brief review on recent progress on the synthesis of an important class of sulfur-heterocycles-2-alkylthiochroman-4-ones and thioflavanones via the conjugate additions of Grignard reagents to thiochromones catalyzed by copper catalysts. Recent progress on the synthesis of 2-substituted thiochroman-4-ones via alkynylation and alkenylation of thiochromones will also be covered in this review.
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The carbon star mystery: 40 years later: Theory and observations
Abstract In 1981 Icko Iben Jr published a paper entitled “The carbon star mystery: why do the low mass ones become such, and where have all the high mass ones gone?”, where he discussed the discrepancy between the theoretical expectation and its observational counterpart about the luminosity function of AGB carbon stars. After more than 40 years, our understanding of this longstanding problem is greatly improved, also thanks to more refined stellar models and a growing amount of observational constraints. In this paper we review the state of the art of these studies and we briefly illustrate the future perspectives.
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- Award ID(s):
- 1927130
- PAR ID:
- 10464917
- Date Published:
- Journal Name:
- The European Physical Journal A
- Volume:
- 59
- Issue:
- 2
- ISSN:
- 1434-601X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1140/epja/s10050-023-00926-8
