D. A. Evans Classification of Functional Groups Chem 206 Functional groups activate the carbon skeleton at the point of attachmentA-Functions: by either induction resonance. A 3rd hypothetical FG, designated as A, may be defined that has an Induction (+ unbiased charge affinity pattem as in 1. Such an idealized FG's activates all C-M1 C-F2 C-F3 CF4 sites to both nucleophilic and electrophilic reactions, and as such include Resonance (+ those functions classifies as either E-or G- The importance of introducing this third class designation is that it includes those functional groups having non-altermate charge affinity pattens such as 2-4 Sy C-E E= electrophilic at the point of attachment Hypothetical A-function A= ambiphilic at the pont of attachment (+-)(+-)(+ G= nucleophilic at the point of attachment For simplicity, we will designate three FG classes according to the designations provided above E& G-Functions. FG-Classification Rules To organize activating functions into common categories it is worthwhile to define hypothetical" functional groups E, and G, having the charge affinity In the proposed classification scheme the following rules followed in the atterns denoted below assignment of class designation of a given FG Hypothetical E-function Hypothetical G-function a Activating functions are to be considered as heteroatoms appended to or included within the carbon skeleton (+)(-)(+) (-)(+)(-) I Activating functions are inspected and classified according to their ation state of the carbon skeleton such functional groups confer icated polar site reactivity patterns toward both electrophiles a Since proton removal and addition processes are frequently an integral aspect of FG activation, the FG, its conjugate acid or base, and its proton Any FG that conforms either to the ideal charge affinity parrern or a tautomers are considered together in determining its class designation sub-pattern thereof will thus be classified as either an E-or G functi I The oxidation state of the FG is deemphasized since this is a subordinate Representative E-functions strategic consideration Me-CH2-CH2-Br Common E-Functions: Symbol: (+)C-E exception: -N H2C=CH-cH2-OHc—C -x, X= halogen Also consider all combinations of of above FGs;e.g=0+ ORC E (+) C F1 (+) (+) C F2 C F3 C F4 C A C G C C C E C C C G CH C O OR H2C H2C CH CH2 OH CH2 C O H Me Me CH2 CH2 Br C C C E1 C C C E2 C C C E3 C C C E4 C C C E C C C A C C A C C A C A OR O O C E NR2 NR N X, X = halogen D. A. Evans Chem 206 ■ Activating functions are to be considered as heteroatoms appended to or included within the carbon skeleton. ■ Activating functions are inspected and classified according to their observed polar site reactivities. ■ Since proton removal and addition processes are frequently an integral aspect of FG activation, the FG, its conjugate acid or base, and its proton tautomers are considered together in determining its class designation. ■ The oxidation state of the FG is deemphasized since this is a subordinate strategic consideration. Induction Resonance (+) (–) (+) (–) (–) (–) Symbol (±) (–) Functional groups activate the carbon skeleton at the point of attachment by either induction & resonance. E = electrophilic at the point of attachment A = ambiphilic at the pont of attachment G = nucleophilic at the point of attachment For simplicity, we will designate three FG classes according to the designations provided above. E & G-Functions: To organize activating functions into common categories it is worthwhile to define "hypothetical" functional groups E, and G, having the charge affinity patterns denoted below. (+) (–) (+) (–) (+) (–) Hypothetical E-function Hypothetical G-function Classification of Functional Groups (–) (+) (–) (+) (+) (+) (+) (+) (+) (–) (+) Given the appropriate oxidation state of the carbon skeleton, such functional groups confer the indicated polar site reactivity patterns toward both electrophiles and nucleophiles. Any FG that conforms either to the ideal charge affinity parrern or a sub-pattern thereof will thus be classified as either an E- or G-function. Representative E-functions: Hypothetical A-function (+–) (+–) (+–) (+) (+) (–) (–) 1 (+–) 2 3 4 FG-Classification Rules A-Functions: A 3rd hypothetical FG, designated as A, may be defined that has an unbiased charge affinity pattern as in 1. Such an idealized FG's activates all sites to both nucleophilic and electrophilic reactions, and as such include those functions classifies as either E– or G–. The importance of introducing this third class designation is that it includes those functional groups having non-alternate charge affinity patterns such as 2–4. In the proposed classification scheme the following rules followed in the assignment of class designation of a given FG. Also consider all combinations of of above FGs; e.g =O + OR exception: exception: Common E-Functions: Symbol: (+)