True or False
1) Under acidic conditions,  -hydroxylalkylsilanes undergo anti-elimination to give Z alkenes ()
2) In HWE reaction, for the choice of solvents, DME usually give higher E-stereoslectivity than THF  ()
3) The Ti-Carbene generated from Tebbe reagent has high reactivity.  It can react with aldehydes, ketones and esters.  ()
4) Vinylstannane can be prepared from hydrostannylation of terminal alkynes ()
5) Julia Olefination usually gives mainly E alkene products  ()
6) In Wittig reaction, stabilized ylides tend to give Z alkene products  ()
7) In Wittig reaction, non-stabilized ylides tend to give E alkene products ()
8) Takai reaction gives high E selectivity ()
Single choice
1) What’s the produc t of below reaction ()
OL, 2001, 3487 A)
B)
C)
D)
2) Which of following functional groups is compatible under McMurry reaction conditions ()
A)Amine
B)Allylic alcohol
C)1,2-diol
D)Sulfoxide
3) Which one of following is a stabilized ylide ()
A)
B)
C)
D)
4) In HWE reaction, which metal counter-ion gives higher E-stereoselectivity at room temperature?  ()                                                              JOC, 1990, 3386
A)Li
reactive carbonyl species
B)Na
C)K
D)Mg
5) In HWE reaction, which of following temperatures gives better E-stereoselectivity? ()
A)-78 ︒C
B)-45 ︒C
C)0 ︒C
D)25 ︒C
6) Which of the following carbonyl groups can react with Tebbe reagent ()
a, aldehyde;      b, ketone;      c, ester;      d, amide
A)All of them;
B)a, b;
C)a, b, c;
D)a, b, d;
7) In Still modification of HWE reaction, which of following does not have contribution on the high Z stereoselectivity?  ()
A)The use of KHMDS as base;
B)Add crown ether (18-C-6) into the system;
C)Use aldehydes with electron-withdrawing groups;
D)Use phosphates with electron-withdrawing groups;
8) In the following HWE reaction, which of following phosphates gives better E stereoselectivity?  ()
Tetrahedron, 1981, 3873 9) In HWE reaction, to obtain higher E stereoselectivity of disubstituted alkene, which of the following statements is NOT correct ()
A)Increase the steric bulkiness of aldehyde;
B)Use Li counter-ion over K;
C)Use lower reaction temperature;
D)Use DME over THF as solvent
10) Please select the product of following transformation ( )
Org. React. 1990, 38, 1
Synthesis, 1984, 384 11) Please select the product of following transformation (    )
12) Please select the conditions for following transformation (Note: without epimerization)  ( )
13) Please select the product of following transformation ()
14) Please address the active species in the Tebbe reaction ()
A)Carbon cation;
B)Carbon anion;
C)Carbene;
D)Radical
)
BMC, 2003, 1169
16) Please select the product of following transformation ()
17) Please select the product of following transformation ()

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