Asymmetric cyclopropanation via catalysts incorporating the 1,4-diol ligands and the newly designed dioxaborolane /

The development of new methodology for the asymmetric synthesis of chiral organic compounds is a major focus in modem organic chemistry. The use of chiral catalysts is replacing chiral auxiliaries as a new tool for synthetic chemists. An efficient chiral catalyst allows for large quantities of optically active product to be obtained on use of relatively small amount of enantiopure material, without the need for the removal and recovery of a chiral auxiliary. Furthermore, the most practical catalytic methods utilize an inexpensive and readily available chiral ligand that can provide high and predictable enantioselectivity across a wide range of substrates. In our project, two type of versatile, upgraded chiral ligands have been designed and synthesized. Their application in Simmons-Smith type cyclopropanation is investigated, and the pleasing results suggest that they are the potential catalytic enantioselective candidates to build C-C bonds.

Letters to the Honourable John H. Dunn, 1837-1838

The recipient of the letters is John Henry Dunn who was born on St. Helena (a British territory island of volcanic origin located in the South Atlantic Ocean) in 1792 to John Charles Dunn and Elizabeth Bazette. He was married to Charlotte Roberts on May 4th, 1820 and they had 6 sons and 2 daughters. He came to Canada in 1820 in which year he became the Receiver General for Canada. He held this position until 1841.Charlotte died in 1835. In 1822 he was named to the Province’s Legislative Council. He was president of the Welland Canal Company from 1825-1833. In 1836 he was named to the executive council of Upper Canada but resigned 3 weeks later with fellow counselors when lieutenant governor Sir Francis Bond refused the advice of the council. Dunn was made the Receiver General for the newly formed Province of Canada in 1841, and was elected to represent Toronto in the legislative assembly that year. He married his second wife on March 9th, 1842. Her name was Sophie-Louise Juchereau Duchsnay. They had a son and a daughter. In 1843 he resigned, and was not re-elected in 1844. He returned to England with his family and died in London on April 21, 1854. Dunn was a supporter of the Welland Canal, St. Lawrence Canals and other public improvements. Between the passage of the Canada Trade Act and the Act of the Union he had tried to insure that projects received funding despite financial constraints. He claimed that he has saved Upper Canada from bankruptcy. His son, Alexander Roberts Dunn received the Victoria Cross for his role in the Charge of the Light Brigade at Balaclava. Dunn Street in Niagara Falls is named after John Henry Dunn. The town and township of Dunnville were also named for him. Sources: http://biographi.ca/009004-119.01-e.php?id_nbr=3889 http://www.niagarafrontier.com/cityfalls.html