How is 4-Chloro-1H-indole-3-carbaldehyde (CAS: 876-72-2) typically synthesized?

4-Chloro-1H-indole-3-carbaldehyde (CAS: 876-72-2) can be synthesized via a multistep process starting from indole. A common method involves the acylation of indole with chloroacetaldehyde followed by the introduction of a chlorine atom using a suitable chlorinating agent. This reaction typically proceeds with a high yield and good selectivity under mild conditions, often utilizing catalytic amounts of a base like sodium bicarbonate.