baldwinsrules

baldwinsrules - BALDWIN'S RULES FOR RING CLOSURE Baldwin's...

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BALDWIN'S RULES FOR RING CLOSURE 135 Baldwin's Rules (Suggestions) for Ring Closure JOC 1977 , 42 , 3846 JCSCC 1976 , 734, 736, 738 Approach Vector Analysis - for an S N 2 displacement at a tetrahedral center, the approach vector of the entering nucleophile is 180° from the departing leaving group L Nu: L Nu Nu :L - for the addition of a nucleophile to an Sp2 center, the nucleophile approaches perpendicular to the π -system. Nu Nu Nomenclature 1. indicate ring size being formed 3 membered ring = 3 4 membered ring = 4 etc. 2. indicate geometry of electrophilic atom if Y= Sp3 center; then Tet (tetrahedral) if Y= Sp2 center; then Trig (trigonal) if Y= Sp center; then Dig (digonal) Y Z X: 3. indicate where displaced electrons end up - if the displaced electron pair ends up out side the ring being formed; then Exo - if the displaced electron pair ends up within the ring being formed; then Endo Y Z X: Exo Z Y X: Endo
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BALDWIN'S RULES FOR RING CLOSURE 136 4. Ring forming reaction is designated as
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baldwinsrules - BALDWIN'S RULES FOR RING CLOSURE Baldwin's...

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