A highly efficient approach to vanillin starting from 4-cresol

A highly efficient approach to vanillin starting from 4-cresol

http://pubs.rsc.org/en/Content/ArticleLanding/2014/GC/C4GC00003J?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00003J, Paper

Jian-An Jiang, Cheng Chen, Ying Guo, Dao-Hua Liao, Xian-Dao Pan, Ya-Fei Ji
A highly efficient three-step approach to vanillin has been developed starting from 4-cresol.

A highly efficient approach to the famous flavor and fragrance compound vanillin has been developed starting from 4-cresol with the attention focused on improving the sustainability of all the reactions. The approach involves a three-step sequence of the quasi-quantitative selective clean oxybromination of 4-cresol, the high-yield selective aerobic oxidation of 2-bromo-4-cresol, and the quantitative methoxylation of 3-bromo-4-hydroxybenzaldehyde with the recovery of pure methanol. Herein, the pivotal oxidation and methoxylation reactions are logically investigated and developed into two concise methodologies. As a green alternative, the approach holds significant value for the sustainable manufacturing of vanillin.

Oxyhalogenation of thiols and disulfides into sulfonyl chlorides/bromides using oxone-KX (X = Cl or Br) in water

A simple and rapid method for efficient synthesis of sulfonyl chlorides/bromides by oxyhalogenation of thiols and disulfides with oxone-KX (X = Cl or Br) using water as the solvent is described.

http://pubs.rsc.org/en/Content/ArticleLanding/2014/GC/C4GC00246F?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00246F, Paper

Sridhar Madabhushi, Raveendra Jillella, Vinodkumar Sriramoju, Rajpal Singh
A simple and efficient method for synthesis of sulfonyl chlorides/bromides by oxyhalogenation of thiols and disulfides with oxone-KX (X = Cl or Br) using water as the solvent is presented

Oxyhalogenation of thiols and disulfides into sulfonyl chlorides/bromides 

using oxone-KX (X = Cl or Br) in water

Aqueous-phase selective hydrogenation of phenol to cyclohexanone over soluble Pd nanoparticles

Aqueous-phase selective hydrogenation of phenol to cyclohexanone over soluble Pd nanoparticles

Green Chem., 2014, Advance Article
DOI: 10.1039/C3GC42408A, Paper

Jing-Fang Zhu, Guo-Hong Tao, Hang-Yu Liu, Ling He, Qian-Hui Sun, Hai-Chao Liu

Corresponding authors

^a

College of Chemistry, Sichuan University, Chengdu 610064, China

^b

College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China

^c

Kunming Sino-Platinum Metals Catalyst Co., Ltd., Kunming 650101, China

The water-soluble Pd nanoparticles are highly-efficient catalysts for the selective hydrogenation of phenol to cyclohexanone in water under mild conditions.

http://pubs.rsc.org/en/Content/ArticleLanding/2014/GC/C3GC42408A?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

The water-soluble metal nanoparticles (NPs) stabilized by poly(N-vinyl-2-pyrrolidone) (PVP) were prepared and examined as catalysts for the one-step selective hydrogenation of phenol to cyclohexanone in water. More than 99% conversion of phenol and selectivity to cyclohexanone was obtained at 90 °C and 1 atm H₂ for 16 h over “soluble” Pd NPs that were reduced by NaBH₄and stabilized by PVP. These Pd NPs were stable, and no leaching or aggregation was detected after five successive runs, showing their advantage for catalyzing the efficient synthesis of cyclohexanone via the one-step selective hydrogenation of phenol under mild conditions.

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The synthesis of Bcr-Abl inhibiting anticancer pharmaceutical agents imatinib, nilotinib and dasatinib

read at
 http://pubs.rsc.org/En/content/articlelanding/2013/ob/c2ob27003j/unauth#!divAbstract

Imatinib (1), nilotinib (2) and dasatinib (3) are Bcr-Abl tyrosine kinase inhibitors approved for the treatment of chronic myelogenous leukemia (CML). This review collates information from the journal and patent literature to provide a comprehensive reference source of the different synthetic methods used to prepare the aforementioned active pharmaceutical ingredients (API's).

A New Compound Against Parkinson's?

Parkinson's is a neurodegenerative disease caused by the loss of dopaminergic neurons, namely nervous cells producing the neurotransmitter dopamine. The death of these cells is, at least partially, due to the excessive synthesis of reactive oxygen species. A promising strategy to counteract this process consists of activating Nrf2 (nuclear factor E2-related factor 2), a protein that stimulates the expression of antioxidant enzymes.
read at
 http://www.chemistryviews.org/details/news/5860841/A_New_Compound_Against_Parkinsons.html

POCl3-mediated H-bonding-directed one-pot synthesis of macrocyclic pentamers, strained hexamers and highly strained heptamers

IU Ying1, QIN Bo2, ZENG HuaQiang1*

1. Department of Chemistry, National University of Singapore, Singapore 117543, Singapore; 2. College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030, China SCIENCE CHINA Chemistry  2012, Vol. 55  Issue (1): 55-63    DOI: 10.1007/s11426-011-4438-0

2012,55(1):55-63   [Abstract] ( 311 ) [PDF 748 KB] ( 1067 )  [Supporting Information]  DOI: 10.1007/s11426-011-4438-0

Previously we have shown that POCl₃-mediated H-bonding-directed one-pot macrocyclization allows for the highly selective preparation of five-residue macrocycles as the predominant product with low yields of hexamers and an undetectable occur-rence of both tetramers and heptamers. Replacing the interiorly arrayed methyl groups with ethyl groups in these 4-7 residue macrocycles alters the relative stability order among them. Specifically, ethoxy-substituted six-residue macrocycle, rather than pentamer, turns out to be computationally the most stable, suggesting that ethoxy-containing hexamer possibly can be formed as the major product under suitable conditions. We have investigated this possibility by varying reaction temperatures and concentrations, invariably affording pentamer as the major macrocycle with strained circular hexamers and highly strained circular heptamers produced in substantial amounts. This discrepancy can be reasonably explained on the basis of bimolecular reactions between two oligomers higher than monomers via kinetic simulations. In this scenario, the acyclic pentamer is ki-netically “trapped” to undergo an intramolecular cyclization to yield circular pentamer, rather than to produce acyclic hexamer. As a result, acyclic hexamer precursor is generated largely from sterically demanding bimolecular reactions between a dimer and a tetramer, or between two trimers that are kinetically slower than the pentamer-producing chain-growth reactions. We ad-ditionally found that one-pot macrocyclization proceeds to the largest extent at 40 °C, an intriguing finding that highlights the low reactivities of acid chloride and amine groups in these H-bond-enforced acyclic oligomeric intermediates.

URL:

http://chem.scichina.com:8081/sciBe/EN/10.1007/s11426-011-4438-0      OR     http://chem.scichina.com:8081/sciBe/EN/Y2012/V55/I1/55