Ask a Librarian

Threre are lots of ways to contact a librarian. Choose what works best for you.

HOURS TODAY

10:00 am - 4:00 pm

Reference Desk

CONTACT US BY PHONE

(802) 656-2022

Voice

(802) 503-1703

Text

MAKE AN APPOINTMENT OR EMAIL A QUESTION

Schedule an Appointment

Meet with a librarian or subject specialist for in-depth help.

Email a Librarian

Submit a question for reply by e-mail.

WANT TO TALK TO SOMEONE RIGHT AWAY?

Library Hours for Monday, June 17th

All of the hours for today can be found below. We look forward to seeing you in the library.
HOURS TODAY
8:00 am - 8:00 pm
MAIN LIBRARY

SEE ALL LIBRARY HOURS
WITHIN HOWE LIBRARY

Maps9:00 am - 4:30 am

Media Services8:00 am - 5:00 pm

Reference Desk10:00 am - 4:00 pm

Cyber Cafe (All Night Study)Closed

OTHER DEPARTMENTS

Special Collections10:00 am - 5:00 pm

Dana Medical Library7:30 am - 11:00 pm

Classroom Technology Services8:00 am - 4:30 pm

 

CATQuest

Search the UVM Libraries' collections

UVM Theses and Dissertations

Browse by Department
Format:
Online
Author:
Srinivasan, Ramya
Dept./Program:
Department of Chemistry
Year:
2018
Degree:
Ph.D.
Abstract:
1-Aza-2-azoniaallene salts, derived by oxidation of substituted hydrazones, are highly reactive cationic heteroallenes. These species participate in several mechanistically distinct reactions including: (1) intramolecular [3+2] cycloadditions, (2) polar [4 +2] cycloadditions, (3) stereospecific C-H aminations, (4) electrophilic aromatic substitutions, and (5) chloroamination reactions. We have shown that this versatile reactivity is governed by the length of the tether and nature of the [pi]-system. A novel intramolecular electrophilic aromatic substitution reaction is observed when the tether length separating the 1-aza-2-azoniaallene salt and a pendant aryl ring is three methylene units to generate alkylaryl azo products. Variations in the electronics and sterics of the heteroallenes greatly affects their reactivity. The azo product obtained from 5-phenyl-pentan-2-one undergoes spontaneous photochemical cleavage, exhibiting interesting applications to this class of compounds. Heteroallenes derived from pent-5-ene-2-one scaffolds undergo a concerted polar [4+2] cycloaddition to give a 1,2,3,4-tetrahydrocinnoline product. These products are structural motifs found in biologically and pharmaceutically active compounds. This reaction can give the structurally complex tetracyclic iminium salt from a cyclohexene based heteroallene which serves as good precedence to the key step of our proposed synthesis of a terpene indole alkaloid, (+)-ibophyllidine.