Synthesis of new chiral alkenyl Fischer carbene complexes

José Barluenga,Javier Santamaría,Miguel Tomás,Narendra Panday,Ana De Prado,Paul Krapcho

doi:10.3998/ark.5550190.0004.a53

José Barluenga, Javier Santamaría + Show 4 more

Open Access

https://doi.org/10.3998/ark.5550190.0004.a53

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Abstract

New chiral group 6 Fischer alkoxycarbene complexes 1 and 2 have been synthesized by condensation of enantiopure aldehydes 6 and 7, respectively, with methylcarbene complexes 5. The corresponding aminocarbene complexes 3 and 4 were accessible from 1 and 2 by methoxypyrrolidine exchange. The chromium carbene 1b underwent the benzannulation reaction with alkynes affording chiral substituted phenols 11.

Highlights

Since their discovery by Fischer1 et al in 1964, Fischer carbene complexes have emerged as powerful organometallic reagents in organic synthesis
We report the synthesis of new chiral alkenyl Fischer carbene complexes 1-4 (Figure 1) derived from optically active reagents that are readily available from the natural chiral pool
The synthesis of the alkoxyalkenylcarbene complexes 1,2 was achieved by diazabicycloundecane (DBU) deprotonation of the carbenes 5, followed by stirring at 0°C with freshly distilled aldehydes 6 or 7

Summary

Introduction

Since their discovery by Fischer1 et al in 1964, Fischer carbene complexes have emerged as powerful organometallic reagents in organic synthesis.2 Among the Fischer carbene complexes, α,β-unsaturated carbenes have been demonstrated to be attractive for synthetic purposes because of their polyfunctional and versatile character.3On the other hand, the development of asymmetric processes based on chiral alkenyl Fischer carbene complexes have received increasing attention.4 incorporation of the chiral auxiliary at the ligands, e.g. chiral phosphines5 and phosphites,6 appears to be the ideal strategy for asymmetric synthesis, it has not been successfully implemented as a practical protocol. We report the synthesis of new chiral alkenyl Fischer carbene complexes 1-4 (Figure 1) derived from optically active reagents that are readily available from the natural chiral pool.

Results

Conclusion