Factor

Approximate order of importance:

Good

Bad

1

FUNCTIONAL GROUP COMPATIBILITY

Conditions compatible with ALL the functional groups present molecule:

Reagent/conditions not compatible or highly risky

2

FUNCTIONAL GROUP EQUIVALENCE

Same functional groups and same or very similar (steric) environment

Functional groups are slightly different/have different steric environment

3

AVAILABILITY

Reagents in already available in lab

Requires buying in reagent.

4a

EXPERIENCE

Personal experience carrying out the reaction (or in the group)

No available experience of the reaction

4b

RELIABILITY OF PROCEDURE

Are the people who have done the reaction well known and reliable?

People reporting the procedure have no known track record.

4c

RELIABILITY OF REACTION TYPE

Is the reaction/reagent type well known with long history

The reaction type/reagent is new or has little widespread use in the literature

5

EASE OF CARRYING OUT THE REACTION

No special apparatus required

Requires special apparatus or handling conditions e.g glovebox.
High pressure vessel/gas cylinder etc

6

COST

Cheap
Note: depends where in sequence reagent occurs: If at end the quantity needed will be small and the substrate more expensive in proportion

Expensive:
Not justifiable for type of transformation
Scale-up of reaction would be too costly for high throughput of material

7

TOXICITY/RISK

Non-toxic reagents required

Uses Toxic reagents:
Heavy metals: Cr/Hg/Sn/Pb/Se/
Toxic organic products: HMPA
Explosive: CH2N2 (and toxic!)

8

COMMERCIAL AVAILABILITY

Reagent commercially available

Reagent requires synthesis

9a

EASE OF SETTING UP THE REACTION

Non anhydrous conditions 

Strict anhydrous conditions required

9b

EASE OF CARRYING OUT THE PURIFICATION

No excess reagents to remove

Large excess of reagents to remove complicating chromatographic purification

9c

EASE OF CARRYING OUT THE WORK-UP

Standard solvent

Uses high boiling point solvent DMF/DMSO/DMPU
that have to be removed