Answers to Arrow-Pushing Problems Vol II
Answers to Arrow-Pushing Problems Vol II
Answers to Arrow-Pushing Problems Vol II
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C343 Prof. Kennan<strong>Answers</strong> <strong>to</strong> <strong>Arrow</strong>-<strong>Pushing</strong> <strong>Problems</strong> <strong>Vol</strong> <strong>II</strong>OLDAOHOOOHO OHH + O OHH +HHOOHOH OH 2H + OH -H +OBOO OOHO O OHOH OH 2LDAHHBO-H +O H OOOEtO OEt OO OOEt OOOO OEtHBOHOOEtOOOOquenchOOPhPhretro-aldol reaction+ PhH +H ++ Phnote that further reactionmight also take place (i.e. aldol)but this is all we need <strong>to</strong> get<strong>to</strong> the given productsOOOOOOCH 3 OOHOretro aldolOHreverse slow(forms strained ring)Opro<strong>to</strong>ntransferO(pro<strong>to</strong>nate enolate thenremove another pro<strong>to</strong>n <strong>to</strong>make new enolate)OH +OHOCH 3OOOHOH<strong>Arrow</strong> pushing answers <strong>Vol</strong>ume <strong>II</strong> – page 1
C343 Prof. KennanOOOOOOOOOCH 3OCH 3HBrOCH 3HO OO OOHOCH 3OHOOCH 3OHOHO- CO 2heatH +H +CH 3 OH 3 C HOOH 3 COHH 3 COH 3 COOOMichael AdditionOOpro<strong>to</strong>ntransferOOOH 3 COOOH 3 COH OCHOH3 HOH 3 COHOOH 3 COOCH 3Mechanism of enolate equilibration by pro<strong>to</strong>n transfer involves taking a pro<strong>to</strong>n from one solvent molecule followedby donation of a pro<strong>to</strong>n <strong>to</strong> another solvent molecule (the reverse order compared <strong>to</strong> pro<strong>to</strong>n transfers in acetal chemistry)CH 3 OHH 3 COHH 3 COH 3 COOOOHOOOOCH 3<strong>Arrow</strong> pushing answers <strong>Vol</strong>ume <strong>II</strong> – page 2
C343 Prof. KennanOLDAOROMichael AdditionOROpro<strong>to</strong>ntransferOROOROHOROHH +HOROHHOH 2HOROHH +HOROH 2HOOOp.t.OOHOH 2 OOOHOOH 2 OOOHp.t.OHOOHOHOO H -H + OOOOOOCH 3 OHCH 3 OOHOHOHHOOOOOO<strong>Arrow</strong> pushing answers <strong>Vol</strong>ume <strong>II</strong> – page 3
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