Question

Which sequence of steps describes the best synthesis of 2-methyl-3-pentanone?

• A. (1) 1-Propanol $+\left( CH _3\right)_2 CHMgBr$, diethyl ether
  (2) $H _3 O ^{+}$
  (3) $PCC , CH _2 Cl _2$
• B. (1) 1-Propanol $+ Na _2 Cr _2 O _7, H _2 SO _4, H _2 O$, heat
  (2) $SOCl _2$
  (3) $\left( CH _3\right)_2 CHCl , AlCl _3$
• C. (1) 1-Propanol + $PCC , CH _2 Cl _2$
  (2) $\left( CH _3\right)_2 CHLi$, diethyl ether
  (3) $H _3 O ^{+}$
  (4) $Na _2 Cr _2 O _7, H _2 SO _4, H _2 O$, heat
• D. (1) 2-Propanol $+ Na _2 Cr _2 O _7, H _2 SO _4, H _2 O$, heat
  (2) $CH _3 CH _2 CH _2 Li$, diethyl ether
  (3) $H _3 O ^{+}$
  (4) $PCC , CH _2 Cl 2$

Answer 1

Answer: (C)

Correct answer is (c) (1) 1-Propanol + $PCC , CH _2 Cl _2$
(2) $\left( CH _3\right)_2 CHLi$, diethyl ether
(3) $H _3 O ^{+}$
(4) $Na _2 Cr _2 O _7, H _2 SO _4, H _2 O$, heat