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Dissertation Information for Narendra Bhalchandra Ambhaikar

NAME:
- Narendra Bhalchandra Ambhaikar

DEGREE:
- Ph.D.

DISCIPLINE:
- Chemistry

SCHOOL:
- Emory University (USA) (2003)

ADVISORS:
- Dennis C. Liotta

COMMITTEE MEMBERS:
- Albert Padwa
- Frank E. McDonald

MPACT Status: Fully Complete

Title: Thiazolidine-2-thione directed diastereoselective additions of chlorotitanium enolates to aldimine derivatives

Abstract: The dissertation describes the diastereoselective addition reactions of chlorotitanium enolates of N -acylated thiazolidine-2-thione chiral auxiliary to various aldimines to form the á,â-disubstituted â-amino carbonyl compounds. Initial work with N -Cbz aldimines reveals the dependence of stoichiometry of titanium tetrachloride and the base (-)-sparteine. Excess titanium tetrachloride leads to higher yields and syn selectivity in all the Cbz imines studied. The same enolates when subjected to reactions with enolizable and non-enolizable O -methyl aldoximes, at higher temperatures and longer reaction times, result in the unusual formation of novel azetine derivatives. These compounds were observed to exhibit anti diastereoselectivity and formed in preference to a six membered ring: dihydropyrimidinone possessing the same anti stereochemistry. The remarkable preference for the formation of four membered rings over that of six membered ring has been ascribed, in part, to the oxophilicity of titanium metal. Opening of the azetine ring by hydrolysis of the C=N double bond leads to the formation of á,â-disubstituted â-amino carbonyl compounds in very high diastereoisomeric ratios. Aldoxime ethers, aldoximes esters, N -silyl aldimines and nitrites have all been observed to form azetine derivatives. Mechanistic investigations pertaining to the reductive cleavage of the N-O bond in the oxime ethers are also discussed.

MPACT Scores for Narendra Bhalchandra Ambhaikar

A = 0
C = 0
A+C = 0
T = 0
G = 0
W = 0
TD = 0
TA = 0
calculated 2008-03-23 20:43:24

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