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True or Fal
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 lectivity ()
Single choice
1) What’s the produc t of below reaction ()
OL, 2001, 3487 A)
B)
C)
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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-stereolectivity at room temperature? () JOC, 1990, 3386
A)Li
历史英文B)Na
C)K
D)Mg
5) In HWE reaction, which of following temperatures gives better E-stereolectivity? ()
challengingA)-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 stereolectivity? ()
A)The u of KHMDS as ba;
B)Add crown ether (18-C-6) into the system;
C)U aldehydes with electron-withdrawing groups;
D)U phosphates with electron-withdrawing groups;
8) In the following HWE reaction, which of following phosphates gives better E stereolectivity? ()
Tetrahedron, 1981, 3873 9) In HWE reaction, to obtain higher E stereolectivity of disubstituted alkene, which of the following statements is NOT correct ()
A)Increa the steric bulkiness of aldehyde;
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B)U Li counter-ion over K;
C)U lower reaction temperature;
D)U DME over THF as solvent
10) Plea lect the product of following transformation ( )
Org. React. 1990, 38, 1
Synthesis, 1984, 384 11) Plea lect the product of following transformation ( )
12) Plea lect the conditions for following transformation (Note: without epimerization) ( )
13) Plea lect the product of following transformation ()
14) Plea address the active species in the Tebbe reaction ()
A)Carbon cation;
B)Carbon anion;
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C)Carbene;
D)Radical
)
BMC, 2003, 1169
16) Plea lect the product of following transformation ()
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17) Plea lect the product of following transformation ()
