Computer assisted analysis of reactions involving organic free radicals and diradicals

Abstract

Recent extensions to the CAMEO program include a mechanistic model for free radical chain reactions. The controlling algorithm treats all reactions as a series of fundamental radical processes, i t . , abstractions, additions, and fragmentations. Chain propagating steps are mimicked by automatic resubmission of selected intermediates. Refinements for integration of biradical processing are described. Several prominent examples that demonstrate the synthetic utility of free radical reactions and the success of the CAMEO program in predicting complex sequences are presented.

Reaction prediction: the suggestions of the Beppe program

“…The flow of the program is roughly sketched in Scheme I. It can be divided into three main parts: (1) the location of Scheme I. Flow of Beppe Program" " REACT is the main routine.…”

“…Example 1. The interaction of acetaldehyde and MeLi gives five first-level products: three of them are expected [enolization (1), a-deprotonation (4), addition (5)]; one [carbonyl deprotonation (3)] is quite feasible; the last [addition of CH2L1 and a proton (2)] is unexpected. At the second level, the enol gives four products: addition of MeLi to the double bond, giving the same unexpected product (7) already discussed; deprotonation of the OH, giving the result complementary to the -deprotonation followed by isomerization (8); the deprotonation of the carbonyl (6); and one product is hypothesized and then eliminated, the substitution of OH with CH2LÍ.…”

Knowledge Discovery in Reaction Databases: Landscaping Organic Reactions by a Self-Organizing Neural Network

“…Another achievement in the application of computers in organic chemistry is the development of a number of computer-assisted synthesis design systems, such as LHASA, WODCA, − and SYNGEN, and reaction prediction systems, such as EROS and CAMEO . In contrast to reaction database systems, both synthesis design and reaction prediction systems are knowledge-based; i.e., they must work with general representations of reaction types rather than with individual reactions.…”