1 of 18. 2 of 18 introduction 3 of 18 motivation virtual synthesis for the assessment of practical...

19
1 of 18

Upload: joshua-porter

Post on 26-Mar-2015

217 views

Category:

Documents


2 download

TRANSCRIPT

Page 1: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

1 of 18

Page 2: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

2 of 18

Introduction

Page 3: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

3 of 18

Motivation

• Virtual synthesis for the assessment of practical chemical hypothesis's.

• What is the set of all molecules available from one-pot type reactions?

• What is the set of all divergent modifications I should make to my scaffold based on starting material availability and synthetic accessibility?

• What is a simple soluble photoacid that can be obtained in two steps from a commercially available materials?

Page 4: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

4 of 18

Can “computational processes-centric chemistry” increase the efficiency with which

human needs are met?

Page 5: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

5 of 18

Mathematical Chemistry

• (Sub)graph isomorphism.• Analytic and constructive enumeration of

graphs (i.e. rooted trees=alkanes).

• Computational complexity of organic synthesis, big “O”, NP-completeness.

Cayley, 1875

Ncarbons 1 2 3 4 5 6 7 8 9 10 11 12 13

Nalkanes 1 1 1 2 3 5 9 18 35 75 159 357 799

Page 6: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

6 of 18

An Atlas Of Click Chemistry

Can such an atlas be queried for quantitative answers to questions like:

• How many molecules are there? How do they cluster?

• What is the “molecular diversity” of this set? Compared to natural products? Top 100 drugs?

• How likely are we to find a new and useful molecule in this set?

• How accurate is the map?

Page 7: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

7 of 18

Every such sequence should be in the atlas.

Sharpless and co-workers, Angew. Chemie, 2001

Page 8: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

8 of 18

Chemically “Easy” ~ Computationally “Easy”

• Only use predictably selective outcomes (to a good chemist’s best knowledge), to avoid the ocean of red-herrings.

• Limiting pathways to < 10 steps, selective outcomes are more predictable, relevant to process and easier to compute.

• This should increase the accuracy and applicability of the atlas.

Page 9: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

9 of 18

Distributions of Molecular Properties, Such As Diversity, Are

Computable

Statements on such properties should be qualified with numbers and labeled axis’,granted the software hasn’t been quite as accessible as it is now.

Page 10: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

10 of 18

Why Is Now A Good Time?

• Maturation of Daylight’s SMILES specification.

• Chemaxon’s set of tools and support, free to academics. Key importance.

Page 11: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

11 of 18

What Can We Do With “Cheap” Starting Materials and “Easy”

Reactions?

Page 12: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

12 of 18

What We Have Now

• A skeleton specification for the set of click reaction implemented in SMIRKS.

• The EPA’s HPV list converted into SMILES, with some additional contributions from internet solicitations.

• Some plumbing that uses Chemaxon’s tools to iterate over molecules/reactions and distributes the workload in a parallel fashion over a cluster.

Page 13: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

13 of 18

Just What Are Click Reactions Specifically?

• Reactions that employ nucleophiles: • Primary amines, monosubstituted sulfonamides, oximes,

hydrazines, hydrazides, thiols, phenols…

• Paired with appropriate electrophiles:

• Primary alkyl halides, tosylates, aldehydes, epoxides, aziridnes…

• Cycloadditions like copper catalyzed acetylene-azide.

• Other reactions such as disulfide formation.

Page 14: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

14 of 18

We Need To Encode All Of These Reactions, Efficiently

• This problem resonates with people who work in programming languages, i.e. how do we specify a large set of graph transformations in a manner that is efficient to encode, debug, update and verify.

• Simple first step is to apply have substitution enabled SMILES.

Page 15: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

15 of 18

lambdaSMILES

• A simple, lightweight preprocesser that makes writing out reaction specifications a little easier. Basically we get macros in SMILES. i.e.

>>N(H)(H)C{@,@@}(H)(CO)(C(=O)O)

N(H)(H)C@(H)(CO)(C(=O)O)

N(H)(H)C@@(H)(CO)(C(=O)O)

Page 16: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

16 of 18

• Hammer out a final computational specification for the click reactions. Some compromises will undoubtedly have to be made. Think in terms of EXCLUDE, REACTIVITY and SELECTIVITY.

• Do we encode some reactions by inserting products as starting materials?

• Check the list manually to ensure that it meets the goal of enriched synthetic accessibility.

• Analyze results, toss structures to VLS.

What Needs To Be Done

Page 17: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

17 of 18

Cool Movie

Page 18: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

18 of 18

Future Directions

• Chemical workgroup productivity, data sharing.

• Computer science of graphical programming languages.

• Machine inference via automatic data collection (ChemCrawler).

• Optimizing global chemical products over sets of chemical processes.

• Chemical education.

Page 19: 1 of 18. 2 of 18 Introduction 3 of 18 Motivation Virtual synthesis for the assessment of practical chemical hypothesis's. What is the set of all molecules

19 of 18

Acknoledgements

• Dr. Peter Kuhn, Scripps-PARC

• Dr. M.G. Finn, Dr. Valarie Fokin and Dr. Barry Sharpless, Scripps