Chiral spiro compounds have been found to have great importance in
organic synthesis because of their presence in a variety of natural alkaloids and
pharmaceuticals. Lately, spiro compounds have gained interest because of their
engrossing conformational characteristics and their structural connection with
biological systems. Enantioselective synthesis of conformationally constrained spiro
and bridged acetals can also be performed by organometallic catalysts but we will
focus on organocatalytic routes in this chapter. Organocatalytic methodologies are
found to be powerful approaches for the synthesis of conformationally rigid spiro and
bridged acetal compounds because of their stability, functional group tolerance and
easy stereoprediction. In this chapter, the organocatalytic asymmetric approaches for
the synthesis of bridged [2.2.1], [2.2.2], [3.1.1], [3.2.1], [3.3.1] bicyclic acetals as well
as spiroacetals are discussed in details with examples. The synthesis contains different
reactions such as Michael addition reaction, Mannich reaction, cycloaddition reaction,
aldol reaction, tandem Friedel Craft/hemiketalization reaction, Knoevenagel, Diels
Alder reaction, cyclisation reaction and various other reactions.
Keywords: Asymmetric, Bridged acetal, Chiral Compounds, Enantioselectivity,
Organocatalysts, Spiro Compounds.
